Blast furnace operation method

Abstract

A method for operating a blast furnace is presented, the method comprising the steps of recovering a blast furnace gas stream from the blast furnace; feeding the blast furnace gas stream and a hydrocarbon containing gas stream to a reforming plant comprising at least one reformer; reforming the blast furnace gas stream and the hydrocarbon containing gas stream in the reforming plant to produce a syngas stream; feeding at least a portion of the syngas stream to the blast furnace, wherein a stream of H2 is added to the hydrocarbon containing gas prior to step (c), and / or to the blast furnace gas stream prior to step (c), and / or to the syngas stream prior to step (d), and / or to the tuyeres of the blast furnace, wherein feeding of at least a portion of the syngas stream is through the shaft of the blast furnace and / or through the tuyeres of the blast furnace, and wherein the efficiency of hydrogen utilization in the blast furnace plant comprising the blast furnace, the reforming plant and the cowper plant is greater than 60%.

Description

[Technical field]

[0001] The present invention relates generally to methods of operating a blast furnace plant, as well as to such a blast furnace plant. [Background technology]

[0002] Although there are alternative methods such as scrap melting and direct reduction in electric furnaces, the blast furnace still represents the most widely used equipment for steel production today. One of the concerns with blast furnaces is the blast furnace gas (BFG), also commonly called "top gas", that comes out of the top of the blast furnace. In earlier times, this top gas could simply have been allowed to be released into the atmosphere, but this has been avoided by using it in BFG-fed power plants, so as not to waste the energy contained in the gas and overload the environment. One of the components contained in blast furnace gas is CO2, which is harmful to the environment and is mainly useless for industrial applications. In fact, waste gases from power plants fed by blast furnace gas contain high CO2 concentrations, typically between 20% and 40% by volume. The blast furnace gas that is combusted usually contains significant amounts of N2, CO, H2O, and H2, in addition to the aforementioned CO2. However, the N2 content varies greatly depending on whether hot blast or (pure) oxygen is used in the blast furnace.

[0003] Primarily to reduce the amount of coke or other carbon sources used, it has been proposed to recover blast furnace gas from the blast furnace, treat it to increase its reduction potential, and inject it into the blast furnace to assist the reduction process. One way to do this is to reduce the CO2 content in the blast furnace gas by Pressure Swing Adsorption (PSA) or Vacuum Pressure Swing Adsorption (VPSA), as disclosed in patent application EP2 886 666 A1. PSA / VPSA equipment can significantly reduce the CO2 content in the blast furnace gas from about 40% to about 5%, but is very expensive to acquire, maintain and operate, and 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 called syngas) that can be used for several industrial purposes. According to the proposed reforming process, blast furnace gas is mixed with a carbonaceous gas containing at least one hydrocarbon (e.g. a lower alkane). In the so-called dry reforming reaction, the hydrocarbons of the gas react with the CO2 in the blast furnace gas to produce H2 and CO. At the same time, the hydrocarbons react with the H2O in the blast furnace gas to also produce H2 and CO in the so-called steam reforming reaction.

[0005] In the interest of reducing CO2 emissions, significant efforts are also being made to reduce the use of carbonaceous fuels for the operation of the blast furnace itself. As an alternative, fuels with increased hydrogen content are being used in the form of hydrocarbons, gaseous hydrogen H2 or mixtures thereof. Due to their high calorific value, hydrogen and hydrocarbons have the potential to be injected into the blast furnace tuyeres as supplementary fuels. The higher the hydrogen contribution to the bosh and shaft gases, the higher the CO2 reduction potential for blast furnace operation will generally be. "Bloom gas" generally corresponds to the gas in the cohesive zone of the blast furnace, while "shaft gas" in this paper corresponds to the gas injected into the shaft of the blast furnace, i.e. above the cohesive zone.

[0006] However, injection of low temperature H2 and / or hydrocarbons through the tuyere at tuyere level together with large amounts of pulverized coal (PCI) leads to a significant decrease in RAFT (raceway adiabatic flame temperature). Higher oxygen enrichment is required to increase RAFT, but is limited by the top gas temperature. Therefore, only a relatively small amount of low temperature H2 and / or hydrocarbons can be injected into the blast furnace through the tuyere, limiting the CO2 saving potential of this technology.

[0007] Injection of hot hydrogen or even hot hydrocarbons such as natural gas at / through the tuyere level could increase hydrogen usage as well as save more CO2 from the blast furnace. However, producing hot hydrogen, and especially hot hydrocarbons, is not technically simple because hydrocarbons tend to crack at high temperatures and steel tends to decarburize and crack when in contact with hot hydrogen.

[0008] In addition, when hydrocarbons and / or hydrogen are injected into the blast furnace, only a portion of the hydrogen is used in the blast furnace to reduce the iron ore, and the rest is discharged from the blast furnace with the top gas, further limiting the benefits of hydrogen and / or hydrocarbon injection. Increasing the amount of hydrogen in the blast furnace by injecting hydrocarbons and / or hydrogen worsens the rate of hydrogen consumption in the blast furnace. This means that the potential for CO2 emission reduction for a given amount of hydrogen decreases as the amount of hydrogen used in the blast furnace increases.

[0009] The last point is particularly problematic when the hydrogen injected into the blast furnace is renewable hydrogen produced from electricity in an electrolysis process. In fact, the use of part of the blast furnace gas leaving a blast furnace plant in a thermal power plant usually leads to a low thermal efficiency of about 25 to 35%. This means that 65 to 75% of the energy of this part of the blast furnace gas is lost when used to produce electricity. It is therefore clear that the use of blast furnace gas for the production of electrical energy should be avoided as far as possible, especially when blast furnace plants utilize expensive carbon-free energy sources such as hydrogen. Summary of the Invention [Problem to be solved by the invention]

[0010] It is therefore an object of the present invention to provide a new method for operating a blast furnace plant as well as a corresponding blast furnace plant, which allows for an efficient utilization of hydrogen in the blast furnace plant, reduces the CO2 emissions resulting from conventional blast furnace steelmaking and at least partially overcomes the above-mentioned problems.

[0011] This object is achieved by a method according to claims 1 and 2 and by a blast furnace plant according to claim 19. [Means for solving the problem]

[0012] In order to achieve the above object, the present invention provides, in a first aspect, (a) recovering a blast furnace gas stream from a blast furnace having a shaft and at least one tuyere; (b) supplying the blast furnace gas stream and the hydrocarbon containing gas stream to a reforming plant comprising at least one reformer; (c) reforming the blast furnace gas stream and the hydrocarbon-containing gas stream in a reforming plant to produce a syngas stream; and (d) feeding at least a portion of the syngas stream to a blast furnace; We propose a method for operating a blast furnace including each step.

[0013] The 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 the mixture comprising blast furnace gas and hydrocarbon-containing gas before step (c) and / or to the syngas stream before step (d). The addition of H2 is done 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 step. The feeding of at least a part of the syngas stream to the blast furnace is performed at / through the shaft level of the blast furnace. The feeding of at least a part of the syngas stream to the blast furnace can also be performed at / through the tuyere level of the blast furnace or through the shaft of the blast furnace and through the tuyere of the blast furnace. In other words, in one embodiment, a part of the syngas stream is fed at the shaft level and another part of the syngas stream is fed simultaneously through the tuyere of the blast furnace, whereas in another embodiment, the feeding of a part of the syngas stream is only through the shaft of the blast furnace.

[0014] In embodiments, additional streams of hydrogen and / or hydrocarbons may be added to the tuyere of the blast furnace.

[0015] Although the process can be applied to the production of other metals such as lead and copper, blast furnaces are normally used only to produce pig iron.

[0016] In the context of the present invention, syngas refers to synthesis gas produced by the reforming process in a reformer.

[0017] In the context of the present invention, a reforming plant comprises at least one reformer. In an embodiment, the reforming plant may comprise a plurality of reformers arranged in series or in parallel with each other, or the reforming plant may comprise a plurality of reformers, at least two in series arranged in parallel with each other, to form at least two trains of reformers. The reformer of the reforming plant may be of any type, for example a regenerative reformer or any type of catalytic dry and / or wet reformer, in particular bottom-heated, side-heated, terraced or top-heated. In an embodiment in which the reforming plant comprises a plurality of reformers, the reformers may be identical to each other or different. The reforming plant may comprise, for example, a pre-reformer and a main reformer. The exact number, type and arrangement of reformers within the reforming plant may be advantageously adapted depending on the level of subsequent feeding of the generated syngas to the blast furnace to meet the requirements of the generated syngas (e.g. temperature, degree of reduction, etc.) or depending on the location of hydrogen addition.

[0018] To carry out the reforming process in the reforming plant, the carbon dioxide and steam sources, for example, the recovered blast furnace gas and the hydrocarbon-containing gas, need to be combined (i.e. mixed) to form a mixed gas before or upon entering the reaction chamber of the first reformer of the reforming plant. In an embodiment in which the reforming plant includes only one reformer, the first reformer corresponds to this reformer.

[0019] The gases reformed in the reactor are a mixture of blast furnace gas and hydrocarbon-containing gas and possibly also steam, which may be more or less well mixed. Combining blast furnace gas with hydrocarbon-containing gas and possibly steam generally means "allowing blast furnace gas to mix with hydrocarbon gas and possibly steam". This may involve (actively) mixing blast furnace gas with hydrocarbon-containing gas and possibly steam, i.e. applying mechanical forces to mix the gases. However, in some cases it may be sufficient to simply inject the gases into a pipe, for example, so that mixing occurs more or less passively by convection and / or diffusion. However, it has been found that the chemical reaction is enhanced by a higher degree of mixing. The gases are combined and mixed in a dedicated vessel, which may be called a mixing vessel or mixing chamber. In an embodiment, it may also be sufficient to inject the blast furnace gas and the hydrocarbon-containing gas and possibly steam separately into the reformer and mix the gases inside the reformer, for example in the pre-chamber of the reformer.

[0020] In one embodiment, the present invention also proposes a method for operating a blast furnace plant by improving the efficiency of hydrogen utilization, which method includes a combination of H2 addition to the blast furnace and reforming reactions, where the hydrogen utilization portion in the blast furnace plant including the blast furnace, the reforming plant and the cowper plant is more than 60% of the hydrogen fed to the blast furnace, and preferably more than 65% of the hydrogen fed to the blast furnace, where the hydrogen fed to the blast furnace is at least 200 Nm3 of the total hot metal produced. 3 / t flow, of which a minimum of 50 Nm3 of molten metal 3 / t is supplied to the blast furnace plant in the form of molecular hydrogen, H2.

[0021] Hydrogen utilization is defined as (hydrogen input to blast furnace plant - hydrogen export from blast furnace plant) / (hydrogen input to blast furnace plant).

[0022] Hydrogen input to a blast furnace or hydrogen fed to a blast furnace plant is defined as the total hydrogen content of the morning glory gas (gas in the cohesive zone of the blast furnace) and the shaft gas injected into the blast furnace. This hydrogen input to the blast furnace includes, inter alia, the hydrogen contained in the syngas, the injected molecular hydrogen H2, other hydrogen-containing gases, the injected coal and / or tar, the moisture of the injected gas and solid fuels, and the moisture of the hot blast.

[0023] Hydrogen export is defined as the hydrogen contained in the blast furnace gas leaving the top of the blast furnace less utilization in the cowper plant and reforming plant, if applicable.

[0024] In another aspect, the present invention proposes a blast furnace plant comprising a blast furnace with a shaft, a tuyere arranged to feed a hydrogen-containing gas stream to the blast furnace, and a gas inlet in the shaft of the blast furnace arranged to feed a syngas stream, preferably a hot syngas stream, to the blast furnace. The blast furnace plant further comprises a reforming plant comprising at least one reformer in fluid communication with the upper part of the blast furnace and a source of hydrocarbon-containing gas, said reforming plant being arranged to convert the blast furnace gas and the hydrocarbon-containing gas stream into a syngas stream and in downstream fluid communication with said gas inlet in the shaft of the blast furnace; and a source of H2 stream in fluid communication with the at least one reformer and / or the gas inlet in the shaft of the blast furnace and / or the tuyere of the blast furnace. In an embodiment, the reforming plant may also be in downstream fluid connection with the tuyere of the blast furnace.

[0025] Advantageously, the blast furnace plant is adapted to operate by carrying out the method according to the first aspect, as described in more detail below.

[0026] Therefore, the present disclosure proposes an integrated method and corresponding equipment that allows to operate a blast furnace with reduced coke and other carbon source ratios, low CO2 emissions, and highly efficient hydrogen (H2) utilization.

[0027] Indeed, the inventors have found that the combined use of hydrogen (H2), blast furnace gas recycling and hydrocarbon reforming can reduce the CO2 emissions of a blast furnace installation without adversely affecting the quality of the metals produced, e.g. pig iron. Thus, one of the main advantages of the present method and installation is that by reconditioning a portion of the blast furnace gas for reuse, the overall CO2 production associated with blast furnace operation can be significantly reduced.

[0028] Another major advantage is that reconditioning a portion of the blast furnace gas for reuse can increase the energy efficiency of the entire blast furnace plant, including the blast furnace, the reforming plant and the cowper plant, thereby improving the hydrogen utilization efficiency. The added H2 is generally not completely consumed in the blast furnace plant, so that at least a portion of the added H2 leaves the blast furnace plant in the export blast furnace gas. Export blast furnace gas means in the present context the remaining blast furnace gas after the blast furnace gas has been consumed in the blast furnace plant, more specifically after it has been consumed in the blast furnace, the cowper plant and the reforming plant. Utilizing the blast furnace gas as fuel gas for at least one reformer burner in the reforming plant also increases the utilization of the blast furnace gas in the blast furnace plant. The blast furnace gas recovered and recycled in the blast furnace plant to produce syngas will be utilized with a very high overall energy efficiency. By reforming, it can be used for metallurgical purposes directly and indirectly in the blast furnace instead of being sent to a thermal power plant, for example. As a result, at least a portion of the outgoing H2 will not be burned to generate energy, e.g. electricity, with low energy efficiency. In other words, less energy is wasted from H2 combustion, improving the overall energy efficiency of H2 utilization.

[0029] In fact, hydrogen production often requires large amounts of energy and is carried out with an efficiency of about 60%. When hydrogen is injected into a blast furnace, only a portion of the hydrogen is used to reduce the iron ore in the blast furnace. Typically, between 30 and 55% of the added hydrogen is used in this reduction, and the remainder leaves the blast furnace in the top gas. The hydrogen contained in the blast furnace top gas is burned to produce electrical energy with an efficiency of about 30%. This results in a "destruction" of 59-69% of the electrical energy used to produce this portion of the hydrogen.

[0030] Reforming technologies, which recover hydrogen at the top of the blast furnace and reuse it in the blast furnace plant with high efficiencies typically exceeding 80%, reduce the proportion of hydrogen used in power generation equipment and therefore the rate of energy destruction.

[0031] Additionally, by injecting the resulting syngas at shaft level of the blast furnace, the coke rate, i.e., the amount of coke and / or other carbon sources per tonne of pig iron produced, can be significantly reduced.

[0032] In addition, the injection of syngas into the shaft of the blast furnace allows for more tuyere injection of pulverized coal, natural gas, and especially hydrogen or other materials, thus replacing excess amounts of coke with hydrogen-enriched auxiliary fuel, thereby further reducing the carbon content of the blast furnace reducing material and, consequently, reducing CO2 emissions.

[0033] Nevertheless, the higher the auxiliary injection rate, the lower the amount of hydrogen used and the more the blast furnace gas needs to be recycled. This problem can be solved by the present method as shown in the preferred embodiment.

[0034] The injection temperature of the syngas through the shaft should be around 950°C, but should not exceed 1050°C in order to avoid melting the materials in the furnace.

[0035] In an embodiment in which the syngas stream fed through the shaft is produced by a reforming plant including at least one reformer at a high temperature level (i.e. typically higher than the temperature level for shaft injection), H2 can advantageously be added to the hot syngas stream downstream of the at least one reformer. The H2 stream thus acts as a coolant for the syngas stream. Using hydrogen in this way, i.e. as a coolant, completely eliminates the need to heat the hydrogen in expensive heating devices before it is injected down the shaft of the blast furnace. In fact, the excess heat of the syngas will be advantageously used to heat the hydrogen. This can increase the efficiency of the process by eliminating the need for both cooling the syngas and heating the hydrogen.

[0036] Additionally, the use of hydrogen in this configuration allows for higher feasible hydrogen injection rates in the blast furnace since the hydrogen is heated in the reformer and injected as part of the syngas at shaft level, i.e. a single hot gas injection system is required to inject both syngas and hydrogen, rather than a separate system to heat the hydrogen to shaft level injection temperature.

[0037] Also, in other industries, the pressure levels of the reformers are relatively high, mostly above 20 barg or even above 40 barg, whereas in blast furnace applications, pressure levels of only 1.5-6 barg are required. This has a significant impact on the operating conditions and limits of the reforming equipment, such as carbon formation and equilibrium conversion. Lower pressure levels favor higher methane conversion at the same temperature level, but unfortunately they also favor the formation of carbon soot. This is why the addition of a H2 stream to the blast furnace gas stream and / or to the hydrocarbon-containing gas upstream of the reformer is particularly advantageous, since it allows partially suppressing the formation of soot, even if it simultaneously reduces the conversion of methane at a certain temperature, compared to the case without the addition of hydrogen.

[0038] Hydrogen may also be added to both the hydrocarbon-containing gas and / or blast furnace gas stream upstream of the reformer and to the syngas stream injected at shaft level. The addition of hydrogen must be balanced between the use of the syngas stream fed through the shaft as a coolant and the addition of hydrogen to the blast furnace gas and / or hydrocarbon-containing gas stream upstream of the reformer for syngas production. As previously mentioned, the addition of hydrogen to the hydrocarbon-containing gas and / or blast furnace gas stream may help reduce soot production during the reforming reaction.

[0039] Another advantage of the method of the present invention for operating a blast furnace is that hydrogen is injected as cold hydrogen (i.e., an unheated stream heated only to temperature levels of economic interest) or pure hot H2 (i.e., without CO2 and / or HO content), thus preventing cracking of the steel.

[0040] The main advantages and benefits of the operating method and blast furnace installation according to the present disclosure can be summarized as follows: Reduce soot formation during the reforming process - Reduction in coke ratio Increased levels of auxiliary fuel injection at the tuyere, and in particular increased levels of injection of hydrogen-containing fuels such as hydrocarbons and / or pure hydrogen. High CO2 savings from replacing fossil fuels with hydrogen Improved blast furnace operation due to the low viscosity of H2, which prevents troubles such as slippage in the shaft and improves the hydrodynamic conditions in the blast furnace cohesive zone with counter flow liquid phase (hot metal and slag falling) / gas phase (gas outflow) in the coke bed. · Improved hydrogen utilization in blast furnace plants through recirculation of blast furnace top gas resulting in increased hydrogen utilization in blast furnace plants.

[0041] These and further advantages of the present method for operating a blast furnace, and the blast furnace installation of the present disclosure are described in further detail below.

[0042] In an embodiment, the disclosed method for operating a blast furnace further comprises the sub-steps of: a1) Optionally hydrogenation and / or desulfurization of hydrocarbon-containing gases and / or blast furnace gas c1) Supply of another portion of the blast furnace gas, alone or mixed with other gases, to the burners of the reformer.

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

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

[0045] The H2 stream and / or the hydrocarbon-containing gas stream and / or the blast furnace gas stream may be heated, in particular any one or all of these streams may be heated before the reforming process, preferably in a heat exchanger that recovers part of the energy of the flue gas coming from the reformer. Preferably, the hydrocarbon-containing gas stream and / or the blast furnace gas stream is preheated (i.e. heated to a moderate temperature) upstream of the reformer. In an embodiment in which the H2 stream is added to the hydrocarbon-containing gas stream and / or the blast furnace gas stream, the H2 stream may be preheated in a dedicated heating device before being added to the hydrocarbon-containing gas stream and / or the blast furnace gas stream. Alternatively, the H2 stream may be preheated simultaneously with the hydrocarbon-containing gas stream and / or the blast furnace gas stream after addition. However, in embodiments where an H2 stream is added to the syngas stream downstream of the reformer, the H2 stream is preferably not heated or is only heated to temperature levels of economic interest, i.e., temperature levels that do not require expensive precautions against attack by hot hydrogen, for example, typically below 600° C. or even below 400° C. In the context of this disclosure, an unheated hydrogen stream, or simply a hydrogen stream heated to a temperature level of economic interest, is referred to as cold.

[0046] In embodiments, desulfurization of the hydrocarbon-containing gas may be necessary depending on its composition. For example, the removal of sulfur requires that in a zinc oxide bed, sulfur is present in inorganic form, more specifically in the form of H2S. However, very often the hydrocarbon-containing gas also contains organic sulfur, which needs to be converted to inorganic sulfur, H2S, in the presence of hydrogen and certain catalysts. Therefore, in embodiments, it may be advantageous to add hydrogen to the hydrocarbon gas even before the hydrogenation step (step a1), in case desulfurization is required. The latter does not necessarily apply to blast furnace gas, since the blast furnace gas itself may contain enough hydrogen for the hydrogenation process.

[0047] Advantageously, a fuel gas comprising a portion of the blast furnace gas and air, respectively for utilization in the burners of at least one reformer of the reforming plant, is also heated in a heat exchanger using a portion of the energy of the flue gas of the reforming process.

[0048] In a preferred embodiment, the H2 stream is produced by electrolysis in an electrolyser. Preferably, the hydrogen is renewable or "green". In the context of the present disclosure, renewable or "green" hydrogen means that it is preferably produced by water and / or steam electrolysis and / or that the power to operate the electrolyser is generated by renewable sources such as wind, solar and / or hydropower.

[0049] The expression "hydrocarbon" or "hydrocarbon-containing gas" in the context of the present disclosure means any hydrocarbon that is in a gaseous state at normal temperatures. Such a hydrocarbon gas thus includes not only natural gas, i.e., a naturally occurring hydrocarbon mixture of fossil origin consisting mainly of methane and generally containing various amounts of other higher alkanes, but also gases with similar hydrocarbon components, such as biogas, coke oven gas, etc. Coke oven gas is a mixture of several gases, mainly hydrogen (i.e., having a hydrogen content of at least 50%), methane (traditionally 25% of coke oven gas), and the rest being a mixture of various gases such as nitrogen, CO, CO2 or H2O. Thus, coke oven gas itself already contains a large amount of hydrogen.

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

[0051] The reformer can be of any type, such as a catalytic reformer, a regenerator type reactor also called a regenerative reformer, a reformer with a plasma torch, a partial oxidation reformer, a reformer with oxygen / carbon and / or hydrocarbon burners.

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

[0053] The reforming process can be carried out catalytically or non-catalytically. In particular, the reforming of natural gas processes can be carried out either catalytically or non-catalytically, while the reforming of coke oven gas is preferably carried out non-catalytically. A catalytically carried out process is carried out in the presence of a catalyst, whereas a non-catalytically carried out process is carried out without a catalyst, i.e. in the absence of a catalyst. The reforming process can further be carried out in a single reformer or in multiple reformers, for example a pre-reformer and a secondary or main reformer.

[0054] The produced syngas needs to be of high quality in order to be effectively utilized in the blast furnace. This quality is usually described by its reduction potential, which is defined as the molar ratio (cCO+cH2) / (cH2O+cCO2). To ensure sufficient quality of the syngas, the reduction potential should be as high as possible, preferably higher than 6, more preferably higher than 7, and most preferably higher than 7.5.

[0055] Thermodynamically, any degree of reduction potential of the syngas can only be achieved by applying a minimum temperature level to the reforming process. The reforming process is preferably carried out at a temperature sufficient for the syngas stream to have both the desired reduction potential and a temperature at which it can be fed through the shaft of the blast furnace. In embodiments where a H2 stream is added to the hydrocarbon-containing gas and / or blast furnace gas stream upstream of the reformer, the addition of hydrogen will help reduce soot formation in the reformer and in the piping from the reformer to the blast furnace, and feed the syngas through the shaft of the blast furnace.

[0056] In addition, the blast furnace gas stream may advantageously be subjected to a gas cooling and / or cleaning and / or pressurization step, preferably a vapour removal step, a dust removal step, a metal removal step, an HCl removal step and / or a sulphur component removal step, before being fed to the reformer.

[0057] In an embodiment, the second stream of blast furnace gas may be used in the burners of the reforming plant, either by itself or mixed with other gases. In a preferred embodiment, as much of the blast furnace gas leaving the blast furnace is recovered as possible for use in the cowper and reforming plant. In other words, as little export blast furnace gas as possible is fed to other units in the steel plant. Preferably so little that use in the thermal power plant is avoided.

[0058] The term "fluid connection" means that two devices are connected by a conduit or pipe so that a fluid, e.g., gas, may flow from one device to the other. This term includes the means for altering this flow, e.g., valves or fans to regulate mass flow, compressors to regulate pressure, etc., as well as control elements, such as sensors, actuators, etc., that are necessary or desirable for proper control of the operation of the blast furnace as a whole or of each element within the blast furnace installation.

[0059] As used herein, "reformer" refers to any vessel capable of carrying out a reforming process, such as a reforming reactor or reforming vessel.

[0060] "Shaft feed", "shaft injection", "feed into the shaft of a blast furnace", "feed at shaft level", "feed through the shaft", "feed at shaft level", "injected at shaft level", or "gas inlet in shaft" means the injection of material (e.g., gas) above the hot blast level, i.e., above the bosh, preferably within the gas solid reduction zone of ferrous oxide above the cohesive zone in a blast furnace.

[0061] "Fed . . . at the tuyere level," "fed . . . through the tuyere," "fed at the tuyere level," or "injected at the tuyere level" means the injection of material (e.g., gas) through the tuyere of a blast furnace.

[0062] In this document, "feed to a blast furnace" and "injection into a blast furnace", as well as "fed to a blast furnace" and "injected into a blast furnace" or "injected into a blast furnace" have the same meaning and are used synonymously, respectively, to refer to the injection of material into a blast furnace.

[0063] In this document, "or" is non-exclusive and means either "or" or "and."

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

[0065] In this document, step (c) refers to reforming in general, which covers the production of syngas for injection either through the shaft or through the tuyeres, as well as the production of syngas for simultaneous injection through the shaft and through the tuyeres.

[0066] Further details and advantages of the present disclosure will become apparent from the following detailed description of some non-limiting embodiments, which refer to the accompanying drawings. [Brief description of the drawings]

[0067] Preferred embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which: [Figure 1] FIG. 2 is a schematic diagram of a first variant embodiment of a blast furnace plant configured to implement the blast furnace operating method. [Diagram 2] FIG. 4 is a schematic diagram of a second variant embodiment of a blast furnace plant configured to implement the blast furnace operating method. [Diagram 3]FIG. 4 is a schematic diagram of a third variant embodiment of a blast furnace plant configured to implement the present blast furnace operating method. [Figure 4] 1 is a graph showing the variation in C2H4 concentration in a reformer as a function of temperature for various hydrogen contents. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0068] CO2 emissions:

[0069] Coke is the main energy input in blast furnace steelmaking. From a CO2 point of view and in many cases also from an economic point of view, it is a less favorable energy source. Alternative energy sources to coke, mainly injected at tuyere level, are widely adopted. However, in countries with low natural gas prices, mainly pulverized coal is injected and this energy is used for cost reasons. In many cases, residues such as waste plastics are also injected into the blast furnace. With the ambition to reduce greenhouse gas emissions, industrial activities have started to incorporate hydrogen as a supplementary fuel, and with the expected high availability of hydrogen, it is expected that the contribution of hydrogen as a supplementary fuel will increase significantly.

[0070] While these auxiliary fuels can have a positive impact on CO2 emissions from blast furnace steelmaking, their use is limited for process reasons and today these limits are very often already reached. Blast furnaces produce blast furnace gas (BFG) which contains up to about 40% of the energy input to the blast furnace. About 25% of the blast furnace gas leaving the blast furnace is usually injected at the tuyere of the blast furnace in the cowper plant and used to heat the blast. The remaining 75% of the blast furnace gas which contains about 30% of the energy input to the blast furnace is usually used for the internal heat requirements of the steel plant but also for electrical energy production.

[0071] Therefore, one of the key strategies to reduce the CO2 emissions of blast furnace based steel production is to use this BFG for metallurgical purposes as much as possible and apply other lean energies, such as green electricity energy, for the remaining energy requirements of the steel plant.

[0072] Therefore, synthesis gas production, together with the utilization of reduced CO2 hydrocarbons, should use blast furnace gas as much as possible, as well as converter gas and / or cold basic oxygen furnace (BOF) gas, if available in the blast furnace plant, to improve the CO2 emission reduction potential from blast furnace steelmaking.

[0073] Hydrogen use for steelmaking:

[0074] The use of hydrogen for steelmaking can be divided into the direct use of hydrogen in the blast furnace, in auxiliary plants, in particular the cowper plant, and, if installed, in a reforming plant to produce syngas which is injected into the shaft of the blast furnace.

[0075] The use of hydrogen in blast furnaces is generally referred to as etaH2. EthaH2 is defined as etaH2=(H2 in BF)-(H2 ​​outside BF in top gas) / (H2 in BF). In this paper, BF means blast furnace, (H2 in BF) refers to the H2 stream entering the blast furnace, and (H2 outside BF in top gas) means the H2 stream in the blast furnace top gas exiting the top of the blast furnace.

[0076] "H2 in BF" is defined as the total hydrogen content of the morning glory gas (gas in the blast furnace cohesive zone) and the shaft gas injected into the blast furnace at the shaft level. This hydrogen input to the blast furnace includes, inter alia, the hydrogen contained in the syngas, in the injected molecular hydrogen H2, in other hydrogen-containing gases, in the injected coal and / or tar, in the moisture of the injected gas and solid fuels, and in the moisture of the hot blast.

[0077] "H2 outside BF in 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] EthaH2 is usually below 50%, often below 45%. Moreover, the EthaH2, and therefore the hydrogen utilization percentage in the blast furnace, has the property that it decreases with increasing hydrogen input to the blast furnace. This means that if one wishes to use more hydrogen in the blast furnace, its utilization efficiency is significantly reduced, and most of the hydrogen introduced to the blast furnace leaves with the top gas. As a result, the coke reduction ratio achievable per kg of injected hydrogen is also reduced, indirectly reducing the CO2 reduction potential of the injected hydrogen.

[0079] Also, increasing the injection of auxiliary fuel (hydrogen-containing gas) requires a higher oxygen enrichment to maintain the flame temperature. Increasing oxygen enrichment in the blast furnace means that less natural blast air is used in the blast furnace. As a result, the total amount of hot blast entering the blast furnace is reduced. This means that less blast furnace gas can be used to heat the hot blast.

[0080] This means that if you increase the percentage of hydrogen in the blast furnace for the reduction of iron ore, a smaller portion of this hydrogen will be used in the blast furnace and a smaller portion will be used in the cowper plant, ultimately resulting in an increase in the amount of hydrogen in the export gas leaving the blast furnace plant.

[0081] This is shown in the following table (Table 1) comparing a baseline operation of a blast furnace with operation of a blast furnace with hydrogen injection according to three embodiments of the method of the present invention.

[0082] [Table 1]

[0083] In the reference operation, the blast furnace uses only coke and pulverized coal injection at the tuyere, but in Case 1, cold hydrogen is additionally injected at the tuyere level of the blast furnace.

[0084] In Case 1, the ratio of hydrogen discharged from the blast furnace plant is 10.045 Nm 3 / h (based on standard) to 14.532Nm 3 / h (for case 1) 4.487Nm 3 The amount of hydrogen fed to the blast furnace increased from 30.322 (relative to the standard) to 41.520 Nm 3 / h (for case 1) 11.198Nm 3 This results in a decrease in hydrogen utilization in the blast furnace plant from 67% to 65%. In other words, the 4.487 Nm3 hydrogen in the top gas from the blast furnace plant 3 is 11.198Nm 3 This corresponds to 40% of the additional hydrogen injected into the blast furnace, and therefore the utilization rate of the additional hydrogen in the blast furnace is much lower, at only 60%.

[0085] In case 2 (Table 1), high temperature syngas at 950 °C is injected at the shaft of the blast furnace. It can be seen that the hydrogen utilization rate at the blast furnace plant increases from 67% to 69%, even though the total amount of hydrogen injected into the blast furnace has increased by more than three times compared to the reference case. This is very impressive because it shows that adding a small amount of hydrogen to the blast furnace at the tuyere level already has an impact on the reduction of the hydrogen utilization rate at the blast furnace plant. Compared to the reference case, the hydrogen utilization rate is increased by 72.703 Nm 3 With the additional injection of hydrogen, the 3 That is, only 30% leaves the blast furnace plant together with the export gas.

[0086] In the last case (case 3) shown in Table 1, the amount of hydrogen entering the blast furnace increases significantly, more than four times compared to the reference case. It can be seen that even now, the utilization rate of hydrogen in the blast furnace plant is high, as in the reference case. 94.984 Nm 3 Of the additional hydrogen injection, 30.304 Nm 3(i.e., only 32%) leaves the blast furnace plant with the export gas.

[0087] Energy efficiency

[0088] In order to achieve a high efficiency of the entire process, it is advisable to equip the cowper plant and the reforming plant with a heat recovery system for preheating the combustion air and / or the combustion gases. The efficiency of both plants should be greater than 70%, more specifically greater than 80%.

[0089] Reforming and Syngas Requirements:

[0090] The requirements for syngas for use in blast furnaces differ from those for other industrial applications.

[0091] The main requirements for using syngas in blast furnaces are:

[0092] Syngas reduction potential and temperature levels

[0093] In other industries, syngas is typically produced, cooled and excess water vapor is separated from the syngas, so that only the cooled gas is used in downstream processes. For existing industrial applications outside the steel industry, the high reduction potential achieved directly by the reforming process is not important. However, in the steel industry, a high reduction potential, preferably as high as possible and at least greater than 6, is highly advantageous, as is the high process efficiency, reduction potential, or degree of reduction, defined as follows: (cCO+cH2) / (cH2O+cCO2), Here, c means molar concentration, e.g., cCO means the molar concentration of CO in syngas, cH2 means the molar concentration of H2 in syngas, cH2O means the molar concentration of H2O in syngas, and cCO2 means the molar concentration of CO2 in syngas.

[0094] Furthermore, a high temperature of the syngas is preferred to allow maximum thermal efficiency, compatible with the temperature levels required for shaft injection through the tuyere and / or shaft. Therefore, the temperature needs to be between 850 and 1100°C, preferably around 950°C, as it is necessary to be able to inject it into the shaft of the blast furnace above the blast furnace cohesive zone, i.e. at shaft level.

[0095] Ratio H2 / CO:

[0096] In the steel industry, as well as other industries, syngas is used for specific applications such as pure hydrogen production, ammonia or other chemical component production, which generally requires a specific ratio of hydrogen and CO in the syngas.

[0097] In comparison, the purpose of using syngas in a blast furnace is the reduction of ore, which is accomplished with both reducing components, CO and hydrogen. Although there is a difference between reducing ore with CO or hydrogen, this difference is relatively small considering that syngas is only a portion of the reducing gas used in the blast furnace.

[0098] Pressure Level:

[0099] Whereas in other industries the pressure levels of the reformers are relatively high, mostly above 20 barg or even 40 barg, in blast furnace applications the required pressure levels are only 1.5-6 barg. This has a significant impact on the operating conditions and limits of the reforming equipment, such as soot formation and equilibrium conversion. At the same temperature level, lower pressure levels are favorable for increasing methane conversion, but unfortunately also favor soot formation, for which reason the addition of a H2 stream to the blast furnace gas stream and / or to the hydrocarbon-containing gas upstream of the reformer is particularly advantageous for partially suppressing soot formation, even if it at the same time leads to a decrease in methane conversion at a given temperature compared to the case without hydrogen addition.

[0100] Hydrogenation:

[0101] As already indicated above, hydrogen can be added simply in the form of H2 at the tuyere of the blast furnace, but also in the form of hydrocarbons. However, hydrogen addition can also be used to positively influence the production of syngas and its injection at the shaft of the blast furnace.

[0102] A stream of hydrogen, preferably renewable hydrogen, is added to the process, especially before the reformer to reduce soot formation, or to the syngas stream after the reformer to cool the syngas stream injected through the shaft and at the same time increase its reduction potential. In this document, when referring to syngas, reduction potential and reduction degree are synonymous, both meaning the molar ratio (cCO+cH2) / (cH2O+cCO2). It may be beneficial to heat the hydrogen stream before adding hydrogen upstream of the reformer.

[0103] Reforming reactions for syngas production:

[0104] Reforming of hydrocarbon gases, such as the reforming of natural gas, may occur primarily through the following reactions:

[0105] Steam reforming in the presence of steam: CH4+H2O=CO+3H2

[0106] Dry reforming in the presence of CO2: CH4+CO2=2CO+2H2

[0107] These two reactions are highly endothermic and require a lot of heat.

[0108] This heat can be provided indirectly by burning a fuel gas and transferring flue gas heat to the reactor, or by coupling the reforming and partial oxidation reactions according to the following equation:

[0109] CH4+1 / 2O2→CO+2H2

[0110] Along with the reforming reactions, side reactions can occur in the reformer. The relative importance of these reactions depends on the operating conditions such as gas composition, temperature and pressure, and the use and nature of the catalyst. The main side reactions at temperatures close to the reforming temperature are:

[0111] Reverse Water Gas Shift Reaction (RWGS): CO2+H2→CO+H2O

[0112] CH4 decomposition: CH4→C+2H2

[0113] Methanation reaction: 4H2+CO2→CH4+2H2O or 3H2+CO→CH4+H2O

[0114] As well as a number of reactions that are part of the reaction scheme for the production of soot / carbon deposits. An example of these reactions is the formation of acetylene, as shown below:

[0115] Formation of acetylene: 2CH4→C2H2+3H2

[0116] This acetylene may be a molecule (precursor) in the production of aromatic hydrocarbons that are part of soot, or it may be pyrolyzed according to the following reaction:

[0117] Decomposition of acetylene: C2H2→2C+H2

[0118] Hydrogen is part of most of these reactions and therefore has a significant influence on the reforming reaction itself as well as on side reactions. Therefore, by adding H2 to the blast furnace gas stream and / or the hydrocarbon-containing gas stream upstream of the reformer, the desirable use of hydrogen in the blast furnace for CO2 abatement purposes can be exploited to further improve the hydrocarbon reforming process, for example by reducing soot formation and deposition.

[0119] Detailed Description of Three Different Embodiments of the Invention In the following, three different variants of the blast furnace and the method of operating the blast furnace plant are presented with reference to the attached drawings.

[0120] FIG. 1 shows a first variant embodiment of the method for operating a blast furnace comprising the simultaneous injection of a first flow of syngas through a shaft of the blast furnace and a second flow of syngas through a tuyere of the blast furnace.

[0121] Blast furnace gas 10 emitted from a blast furnace 12 is recovered at the top (upper part) of the blast furnace 12 .

[0122] The recovered blast furnace gas 10 is generally pre-treated as it leaves the blast furnace. Pre-treatment of the blast furnace gas stream includes first cooling, cleaning to reduce the steam content, in particular removing dust and / or HCl and / or metal compounds, then final desulphurization, heating, reforming processes and pressurization to obtain a pressure sufficient for injection in the blast furnace. In the embodiment of FIG. 1, the cooling, cleaning and pressurization of the blast furnace gas is performed in a cooling, cleaning and pressurization unit 14. Alternatively, separate units can be used, each performing one of the cooling, cleaning or pressurization of the blast furnace gas. In other embodiments, one unit is responsible for both cooling, cleaning and pressurization of the blast furnace gas, and the third pre-treatment step is performed in another unit. In this document, a cooling, cleaning and pressurization unit is a unit configured to cool, clean and pressurize the gas stream, without any assumption that the various steps (cooling, cleaning and pressurization) must be performed in that order. In an embodiment, such as for example an embodiment in which the cleaning of the gas stream is desulphurization, the pressurization is performed upstream of the cleaning.

[0123] Downstream of the cooling, washing and pressurizing unit 14, the blast furnace gas stream is split into three streams. A first stream of blast furnace gas 16 is fed to a first reforming plant 18 and a second stream of blast furnace gas 20 is fed to a second reforming plant 22. In this embodiment, both reforming plants are regenerative reforming plants. A third stream of blast furnace gas 27 is called export gas and corresponds to the blast furnace gas fed to another unit of the steel plant including a blast furnace plant with reforming plants 18, 22.

[0124] In addition, a coke oven gas and / or natural gas stream 24 is fed to the reforming plants 18,22.

[0125] Basic oxygen furnace gas and / or steam may optionally be added to the blast furnace gas stream (upstream and / or downstream of the cooling, scrubbing and pressurizing unit 14) and / or to the hydrocarbon-containing gas stream 24 and / or to the direct reforming plants 18, 22 (not shown).

[0126] Reforming of the first stream of blast furnace gas 16 with a coke oven gas and / or natural gas stream 24 takes place in a first reforming plant 18 to produce a first stream of syngas 26. Reforming of the second stream of blast furnace gas 20 with a coke oven gas and / or hydrocarbon containing gas stream 24 takes place in a reforming plant 22 to produce a second stream of syngas 28.

[0127] Both reforming processes are dry and / or wet reforming processes, possibly in combination with partial oxidation, leading to the formation of two streams 26, 28 of syngas rich in CO and H2 content. The reforming processes are carried out at pressures between 1.5 and 10 barg and at temperatures above 900°C, preferably above 950°C, more preferably above 1000°C depending on the reforming plant.

[0128] The blast furnace gas and / or hydrocarbon containing gas may optionally be heated (not shown) prior to the reforming process. Heating may be accomplished using, for example, tube bundle heat exchangers. A second stream 28 of syngas from the second reforming plant 22 is fed to the blast furnace through tuyere 30 with a temperature of about 1200° C. and a pressure of 2-6 bar.

[0129] In addition, the blast furnace facility includes an electrolyzer 32 that is energized by electricity 34 to produce an H2 stream 36 by electrolysis, preferably by water / steam electrolysis. The electricity 34 that powers the electrolyzer 32 is preferably renewable or "green", i.e. derived from renewable sources such as wind, solar and / or hydropower.

[0130] Alternatively or additionally, the hydrogen can be produced from natural gas by a pyrolysis process with solid carbon formation, or a combination of carbon capture and storage (CCS) and / or carbon capture and utilization (CCU) technologies. Hydrogen can also be produced by steam methane reforming or methane thermal cracking in combination with CCS and / or CCU technologies.

[0131] The H2 stream 36 produced in the electrolyser is added to the first stream of syngas 26 downstream of the first reforming plant 18 and upstream of a gas inlet 38 located through the shaft inside the blast furnace 12. The first stream of syngas 26 with added hydrogen 36 forms an H2-enriched gas stream 40 which is fed to the blast furnace through the gas inlet 38 at shaft level at a temperature of about 900°C and with a typical pressure of 1.5-4 bar.

[0132] The H2 stream 36 acts as a coolant for the first stream of syngas 26. Using the hydrogen in this manner, i.e. as a coolant, completely eliminates the need to heat the hydrogen in expensive heating equipment before injecting it through the shaft of the blast furnace 12. In fact, the excess heat of the syngas 26 heats the hydrogen. This eliminates the need for both syngas cooling and hydrogen heating, making the process more efficient.

[0133] FIG. 2 illustrates a second variant embodiment of the method for operating a blast furnace, which includes simultaneous injection of a first flow of syngas through the shaft of the blast furnace and a second flow of syngas through the tuyere of the blast furnace.

[0134] Blast furnace gas 110 emitted from the blast furnace 112 is collected at the top of the blast furnace 112 .

[0135] The recovered blast furnace gas 110 is generally pre-treated as it leaves the blast furnace. Pre-treatment of the blast furnace gas stream includes first cooling to reduce its steam content, cleaning, in particular removing dust and / or HCl and / or metal compounds and / or sulfurous components, and pressurizing to have sufficient pressure for the subsequent reforming process and injection into the blast furnace. In the embodiment of FIG. 2, the cooling, cleaning and pressurization of the blast furnace gas is performed in a cooling, cleaning and pressurization unit 114. Alternatively, separate units may be used, each unit either cooling, cleaning or pressurizing the blast furnace gas. In another embodiment, one unit is responsible for two of the cooling, cleaning and pressurization of the blast furnace gas, and the third pre-treatment step is performed in another unit.

[0136] Downstream of the cooling, washing and pressurizing unit 114, the blast furnace gas stream is split into three streams. A first blast furnace gas stream 116 is fed to a first reforming plant 118 and a second blast furnace gas stream 120 is fed to a second reforming plant 122. In this embodiment, both reforming plants are regenerative reforming plants. A third blast furnace gas stream 127 is called blast furnace exit gas and corresponds to the blast furnace gas fed to another unit of the steel plant including a blast furnace plant with reforming plants 118, 122.

[0137] In addition, the blast furnace facility includes, in addition to the blast furnace and the cooling, washing and pressurizing unit 114, a source of coke oven gas and / or natural gas stream 124 in fluidic communication with each of the reforming plants 118, 122, and an electrolyzer 132 powered by electricity 134 to produce an H2 stream 136 by electrolysis, preferably water electrolysis. The electricity 134 that powers the electrolyzer 132 is preferably renewable or "green", i.e. derived from renewable sources such as wind, solar and / or hydropower.

[0138] The H2 stream 136 produced by the electrolyzer is added to the coke oven gas and / or natural gas stream 124 upstream of the reforming plants 118, 122 and fed to each of the reforming plants 118, 122 to form an H2-enriched hydrocarbon-containing gas stream 142.

[0139] Basic smelter gas and / or steam may optionally be added to the blast furnace gas stream (upstream and / or downstream of the cooling, scrubbing and pressurizing unit 114) and / or to the hydrocarbon-containing gas stream 124 and / or to the H2 stream 136, and / or to the direct reforming plants 118, 122 (not shown).

[0140] In the first reforming plant 118, the first stream 116 of blast furnace gas is reformed with a H2-rich hydrocarbon-containing gas stream 142 to produce a first stream 126 of syngas. In the second reforming plant 122, the second stream 120 of blast furnace gas is reformed with a H2-rich hydrocarbon-containing gas stream 142 to produce a second stream 128 of syngas.

[0141] Both reforming processes are dry reforming and result in the formation of two streams of syngas 126, 128 with high CO and H2 content. The reforming processes are carried out at pressures between 1.5 and 10 barg and at temperatures above 900°C, preferably above 1000°C, more preferably above 1200°C, depending on the reforming plant.

[0142] The blast furnace gas and / or hydrogen-containing gas may optionally be heated (not shown) prior to the reforming process. Heating may be accomplished, for example, using a shell-and-tube heat exchanger.

[0143] Adding hydrogen to the hydrocarbon-containing gas upstream of the reforming plant 118, 122, and thus prior to the reforming process, will help reduce the formation of soot during the reforming reaction. The formation of carbon deposits with dry reforming is a known problem. Different reactions take place in the reforming plant and result in the formation of carbon deposits. Many of these reactions include the formation of ethene C2H4 and acetylene C2H2 precursors. The formation of these precursors from methane leads to the separation of hydrogen and an increase in gas volume. Therefore, the formation of carbon deposit precursors and thus the carbon deposits themselves can be reduced by adding H2 to the gas mixture being reformed, such as by increasing the partial pressure of hydrogen in the reactor inlet gas, i.e., by adding H2 to the hydrocarbon-containing gas and / or to the syngas stream. For example, as shown in FIG. 4, by increasing the amount of H2 in the reforming gas mixture from 10% to 40%, the C2H4 concentration in the reforming plant is significantly reduced from about 0.35% to about 0% at 1225° C.

[0144] A first stream 126 of syngas exiting the second reforming plant 118 is fed to the blast furnace through a gas inlet 138 disposed through the interior shaft of the blast furnace 112 with a temperature of about 950° C. and a pressure of 1.5 to 4 bar (i.e., the second stream 126 of syngas is fed through the shaft of the blast furnace). Depending on the reforming process, the second stream of syngas may be cooled to a temperature of about 950° C. before being fed through the shaft of the blast furnace.

[0145] A second stream 128 of syngas exiting the second reforming plant 122 is fed to the blast furnace through tuyere 130 with a temperature of about 1200° C. and a pressure of 2-6 barg.

[0146] FIG. 3 illustrates a third embodiment of the present method for operating a blast furnace, which also includes simultaneous injection of a first stream of syngas through the shaft of the blast furnace along with injection of low temperature hydrogen and / or hydrocarbon containing gas, and possibly pulverized coal through the tuyere of the blast furnace.

[0147] Blast furnace gas 210 exiting the blast furnace 212 is collected at the top of the blast furnace 212 .

[0148] The recovered blast furnace gas 210 is generally pre-treated upon exiting the blast furnace in a gas washing and cooling unit 214. Pre-treatment of the blast furnace gas stream first involves cooling to reduce its steam content, washing, and in particular removing dust and / or HCl and / or metal compounds.

[0149] A portion of the cleaned blast furnace gas 219 is used as part of the fuel, together with moist air 223, and often with other high heat gases (not shown) in the burners of the cowper plant 221, to heat the hot blast that is injected into the blast furnace at its tuyere level. Both the gas and the air may or may not be preheated.

[0150] Another portion of the blast furnace gas 217 is used as part of the fuel, together with moist air 223, and often other highly heat-generating gases (not shown), in the burners of the reforming plant 218. Both the gas and the air may or may not be preheated.

[0151] Another blast furnace gas stream 216 is used in the reforming reaction. This stream is further fed to a compressor 215 for compressing the blast furnace gas to the pressure levels required for reforming and injection into the blast furnace.

[0152] The remaining blast furnace gas leaving the blast furnace 212 that is not used in either the reforming plant or the cowper plant is called blast furnace exit gas 227 and is supplied to other units within the steel plant, including the blast furnace 212.

[0153] In the embodiment of FIG. 3, optionally after the compressor (compression unit) 215 there is also a hydrogenation and desulfurization unit 250 .

[0154] Additionally, a coke oven gas and / or natural gas stream 224 is fed to the reforming plant 218. The gas 224 may be desulfurized in a desulfurization unit 250. The desulfurization of the gas 224 may occur in parallel with the desulfurization of the blast furnace gas (FIG. 3). Alternatively, the gas 224 may be desulfurized in a separate desulfurization unit (not shown). In such an embodiment, hydrogen may be added to the natural gas for hydrogenation of organic sulfur contained therein (not shown).

[0155] Basic smelter gas and / or steam 225 may optionally be added to the blast furnace gas stream (upstream and / or downstream of the pressurization unit 215), to the hydrotreating and desulfurization unit 250, to the hydrocarbon-containing gas stream 224 (not shown) and / or directly to the reforming plant 218 or after the reforming plant 224.

[0156] Reforming of the blast furnace gas stream 216, along with a coke oven gas and / or natural gas stream 224, takes place in a reforming plant 218 to produce a syngas stream 226. The two gas streams, the blast furnace gas 216 and the hydrocarbon containing gas, need to be mixed before entering the reforming plant 218, within the reforming plant 218 and / or before entering the hydrotreating and desulfurization plant 250.

[0157] The reforming process is a dry and / or wet reforming process, possibly in combination with partial oxidation, resulting in the formation of a syngas stream 226 rich in CO and H2 content. The reforming process is carried out at a pressure between 1.5 and 10 barg and at a temperature above 900°C, preferably above 950°C, more preferably above 1000°C depending on the reforming plant.

[0158] The blast furnace gas and / or the hydrogen-containing gas may optionally be heated prior to the reforming process (not shown). Heating may be done, for example, using a shell-and-tube heat exchanger that transfers part of the heat of the flue gas from the reforming plant. The same applies to the mixed gas comprising the blast furnace gas and the hydrocarbon-containing gas entering the reforming plant, which is also preferably heated to at least 350° C., more preferably above 400° C., and preferably above 450° C. Optionally, the blast furnace gas and air used in the burners of the cowper plant and / or the reforming plant may also be a heated transfer part of the heat of the flue gas from the reforming plant in a heat exchanger, for example a shell-and-tube heat exchanger.

[0159] In addition, the blast furnace facility includes an electrolyzer 232 that is energized by electricity 234 to produce an H2 stream 236 by electrolysis, preferably by water / steam electrolysis. The electricity 234 that powers the electrolyzer 232 is preferably renewable or "green", i.e., derived from renewable sources such as wind, solar and / or hydroelectric power.

[0160] Alternatively or additionally, the hydrogen can be produced from natural gas by a pyrolysis process with solid carbon formation, or by a combination of Carbon Capture and Storage (CCS) and / or Carbon Capture and Utilization (CCU) technologies. Hydrogen can also be produced by methane pyrolysis or steam methane reforming in combination with CCS and / or CCU technologies.

[0161] The H2 stream 236 produced by the electrolyser, or a portion thereof, is added to the coke oven gas and / or natural gas stream 224 upstream of the reforming plant 218 to form an H2-enriched hydrocarbon-containing gas stream which is fed to the reforming plant 218, and / or a portion thereof is fed to the hydrocarbon-containing gas stream prior to the hydrogenation step, and / or fed at low temperature at the tuyere of the blast furnace, alone or together with other auxiliary fuels such as coal, natural gas, plastics, biomass, etc.

[0162] Basic smelter gas and / or steam may optionally be added to the blast furnace gas stream (upstream and / or downstream of the pressurization unit 215 or hydrogenation unit 250) (not shown) and / or to the hydrocarbon-containing gas stream 224 (not shown) and / or to the H2 stream 236 (not shown) and / or directly to the reforming plant 218 or after the reforming plant 218.

[0163] A portion of the H2 stream 236 may be added to the syngas stream 226 downstream of the reforming plant 218 and upstream of a gas inlet 238 located through the shaft inside the blast furnace 212. The syngas stream 226 with the addition of hydrogen 236 forms an H2-enriched gas stream 240, which is fed to the blast furnace through the gas inlet 238 at shaft level with a temperature of about 900° C. and a typical pressure of 1.5 to 4 bar.

[0164] A portion of the hydrogen 236 and / or hydrocarbon containing gas 224 may be injected directly through the blast furnace tuyeres 230. In an embodiment, the injection of the hydrogen 236 and / or hydrocarbon containing gas 224 may be performed in conjunction with the injection of a solid fuel, such as pulverized coal injection 229.

[0165] A portion of the H2 stream 236 may be used as a coolant for the first stream of syngas 226. In this manner, i.e., using the hydrogen as a coolant, the need to heat the hydrogen in expensive heating equipment before injecting it through the shaft of the blast furnace 212 may be completely eliminated. In fact, the excess heat of the syngas 226 heats the hydrogen. This eliminates the need for both syngas cooling and hydrogen heating, increasing the efficiency of the process.

[0166] While the invention has been illustrated and described in detail in the drawings and the foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art, from a consideration of the drawings, the disclosure, and the appended claims, when practicing the claimed invention. [Explanation of symbols]

[0167] 10,110,210 Blast furnace gas flow 12,112,212 blast furnace 14,114,214 Cooling, cleaning and pressurizing units 16,116,216 First stream of blast furnace gas 18,118,218 First Reforming Plant 20,120 Second stream of blast furnace gas 22,122 Second reforming plant 24,124,224 Coke oven gas and / or natural gas stream 26,126,226 Syngas 1st stream 27,127,227 Blast furnace discharge gas 28,128 Syngas second stream 30,130,230 Blast furnace tuyere level 32,132,232 Electrolytic cell 34,134,234 Electricity 36,136,236 H2 style 38,138,238 Gas inlet through the shaft of a blast furnace 40,240 H2-enriched stream of syngas 142 H2-enriched stream of hydrocarbon-containing gas 215 Pressurizing unit (compressor) 217 Blast furnace gas supplied to the burners of a reforming plant 219 Blast furnace gas supplied to the burners of a cowper plant 221 Cowper Plant 223 Humid Air 225 Water Vapor 229 Pulverized Coal 250 Hydrogenation and Desulfurization Unit

Claims

1. a. recovering a blast furnace gas stream (16, 116, 216) from a blast furnace (12, 112, 212) having a shaft and at least one tuyere; b. feeding said blast furnace gas stream (16, 116, 216) and said hydrocarbon containing gas stream (24, 124, 224) to a reforming plant comprising at least one reformer (18, 118, 218); c. reforming said blast furnace gas stream (16, 116, 216) and said hydrocarbon-containing gas stream (24, 124, 224) in a reforming plant (18, 118, 218) to produce a syngas stream (26, 126, 226); and d. feeding at least a portion of said syngas stream (26, 126, 226) to a blast furnace (12, 112, 212); A method for operating a blast furnace (12, 112, 212) including each step, H ２ Stream (36, 136, 236) is added to the hydrocarbon-containing gas (24) prior to step (c), and / or to the blast furnace gas stream (16) prior to step (c), and / or to the mixture comprising blast furnace gas and hydrocarbon-containing gas prior to step (c), and / or to the syngas stream (26) prior to step (d), and The method of operating a blast furnace, wherein feeding at least a portion of said syngas stream (26) to the blast furnace is through a shaft (38) of the blast furnace.

2. A method for operating a blast furnace (212) by improving the efficiency of hydrogen utilization in the blast furnace (212), comprising: ２ including a combination of addition and reforming reactions, the portion of hydrogen utilization in the blast furnace plant, including the blast furnace (212), the reforming plant (218) and the cowper plant (221), exceeds 60% of the hydrogen fed to the blast furnace, and preferably exceeds 65% of the hydrogen fed to the blast furnace; Hydrogen utilization is defined as (hydrogen input to blast furnace plant – hydrogen output from blast furnace plant) / (hydrogen input to blast furnace plant), The hydrogen input to the blast furnace is defined as the total hydrogen content of the gas in the blast furnace cohesive zone and the shaft gas injected into the blast furnace at the shaft level (240); and The hydrogen supplied to the blast furnace must be at least 200 Nm3 of the total molten metal produced. ３ / t flow, of which a minimum of 50 Nm3 of molten metal ３ / t is hydrogen molecule H ２ (236) to the blast furnace plant, The hydrogen fed to the blast furnace is in particular syngas (226), injected molecular hydrogen H ２ (236), other hydrogen-containing gases (224), hydrogen contained in the injected coal and / or tar, moisture from the injected gas (224) and solid fuel (229), and moisture from the hot air (230); A method for operating a blast furnace (212).

3. 2. The method of claim 1, wherein feeding at least a portion of the syngas stream (26) to the blast furnace occurs through a shaft (38) of the blast furnace and through at least one tuyere (30) of the blast furnace.

4. 3. The method according to claim 1 or 2, wherein at least a portion of the hydrogen supplied to the blast furnace plant is injected through the tuyere of the blast furnace.

5. 3. The method of claim 1 or 2, wherein feeding at least a portion of the syngas stream (26) to the blast furnace is through a shaft (38) of the blast furnace and through a tuyere (30) of the blast furnace.

6. H ２ 3. The method of claim 1 or 2, wherein the stream (36, 236) is added to a syngas stream (26, 226) with a temperature below 600°C.

7. 3. The process according to claim 1 or 2, wherein the blast furnace gas stream and / or the hydrocarbon-containing gas stream is hydrogenated and / or desulfurized in a hydrogenation and desulfurization plant (250) upstream of the reforming plant (218).

8. 8. The method of claim 7, wherein at least a portion of the hydrogen is added to the hydrocarbon-containing gas stream upstream of the hydrotreating and desulfurizing unit (250).

9. H ２ 3. The method of claim 1 or 2, wherein the stream (36) is produced by electrolysis in an electrolytic cell (32).

10. 10. The method of claim 9, wherein the electricity (34) for operating the electrolyser (32) is generated by renewable sources such as wind, solar and / or hydroelectric power.

11. 3. The method of claim 1 or 2, wherein the hydrocarbon-containing gas (24) comprises natural gas, coke oven gas and / or biogas.

12. 3. The method according to claim 1 or 2, wherein at least one reformer of the reforming plant (18) is a regenerative reformer.

13. 3. The method according to claim 1 or 2, wherein at least one reformer of the reforming plant (18) is any type of catalytic dry and / or wet reformer, in particular bottom-heated, side-heated, terraced or top-heated.

14. 3. The method according to claim 1 or 2, wherein the reforming plant (18) comprises two reformers, in particular a pre-reformer and a main reformer.

15. 3. The process according to claim 1 or 2, wherein the reforming in step (c) is carried out non-catalytically.

16. 3. The process according to claim 1 or 2, wherein the reforming in step (c) is combined with partial oxidation of the hydrocarbon.

17. The syngas (26, 28) produced in step (c) has a reduction potential greater than 6, preferably greater than 7, more preferably greater than 7.5, and the reduction potential is (cCO + cH ２ ) / (cH ２ O + cCO ２ 3. The method of claim 1 or 2, wherein said first and second aryl groups are defined by the formula:

18. 3. The process of claim 1 or 2, wherein the reforming in step (c) is carried out at above about 900°C, preferably above about 950°C, more preferably above about 1000°C.

19. 3. The process according to claim 1 or 2, wherein the blast furnace gas stream (10) is further subjected to a gas cooling and / or cleaning and / or pressurization step, preferably a steam removal step, a dust removal step, a metal removal step, a HCl removal step and / or a sulfur removal step, before being fed to the reformer (18).

20. 3. The process according to claim 1 or 2, wherein after the scrubbing step a steam flow is added to the hydrocarbon-containing gas (24) and / or a steam flow is added to the blast furnace gas.

21. 3. A process according to claim 1 or 2, in which the blast furnace gas stream is used in a burner of a reforming plant.

22. 1. A blast furnace plant comprising a blast furnace (12, 112, 212) having a shaft, a tuyere arranged to supply a first flow of hydrogen-containing gas to the blast furnace, and a gas inlet in the shaft of the blast furnace arranged to supply a syngas flow to the blast furnace, at least one reformer in fluid communication with an upper portion of the blast furnace (12, 112, 212) and with a source of hydrocarbon-containing gas (24, 124, 224), the reformer being arranged to convert the blast furnace gas and the hydrocarbon-containing gas stream into a syngas stream, the reformer being in fluid communication downstream with said gas inlet in the shaft of the blast furnace; and At least one reformer and / or a gas inlet in the shaft and / or a H in fluid communication with the tuyere of the blast furnace. ２ flow source (36,136,236); The blast furnace plant further comprises:

23. 23. A blast furnace installation as claimed in claim 22, configured to carry out a method for operating a blast furnace as claimed in any one of claims 1 to 21.

24. 24. The blast furnace installation of claim 22 or 23, wherein the reformer is in downstream fluid connection with a tuyere of the blast furnace and a gas inlet in the shaft of the blast furnace.

25. 24. A blast furnace installation according to claim 22 or 23, wherein the reforming plant (18) comprises a regenerative reformer.

26. 24. A blast furnace installation according to claim 22 or 23, wherein the reforming plant (18) comprises a catalytic dry and / or wet reformer and / or the reforming plant (18) comprises two reformers, in particular a pre-reformer and a main reformer.

27. 24. The blast furnace installation according to claim 22 or 23, wherein the reforming plant (18) further comprises a partial oxidation reformer.

28. 24. A blast furnace installation according to claim 22 or 23, further comprising a gas cooling and / or washing and / or pressurizing plant arranged in fluid connection with the upper part of the blast furnace for transferring the blast furnace gas stream to the upgrading plant, preferably a steam removal unit, a dust removal unit, a metal removal unit, an HCl removal unit and / or a sulfur component removal unit.

29. 24. A blast furnace installation according to claim 22 or 23, further comprising a pressurization unit (215) and / or an oxygenation and desulfurization unit (250) in fluid connection with the upper part of the blast furnace arranged for transferring the blast furnace gas stream to a reforming plant.

Images