Co-injection of hydrogen and biomass to achieve decarburization in iron making process

Abstract

A method of manufacturing a carbon neutral steel is disclosed. The method comprises: injecting a non-carbon or carbon neutral fuel comprising at least one combustible gas and a solid carbonaceous material into a tuyere; combusting at least a portion of the at least one combustible gas; blowing the fuel, gas and combustion products into the furnace; and reducing blast furnace charge to produce slag and molten steel, wherein the at least one combustible gas and the solid carbonaceous material are co-injected into the tuyere through a lance in fluid communication with the tuyere. The invention also relates to a system for co-injecting the non-carbon or carbon-neutral fuel into a steelmaking furnace, a lance for co-injecting the fuel, and a method of using the system.

Description

Technical Field

[0001] The present invention relates to a method for co-injecting a carbonaceous material and a fuel gas into a blast furnace, and a lance for such co-injection. Background Art

[0002] As a major ironmaking facility accounting for more than 70% of pig iron production, the blast furnace is one of the largest carbon dioxide emitters. In the ironmaking process, traditional fuels are all carbon sources, such as metallurgical coke and pulverized coal for heating and iron ore reduction purposes. In a known embodiment, pulverized coal injection (PCI) involves injecting pulverized coal or coal fines into the furnace through tuyeres for combustion and production of reducing gases. Injecting coal in this way partially replaces the coke in the furnace, thus significantly reducing the use of coke and thereby reducing the environmental impact and / or cost of the additional coking step. However, applying PCI in the blast furnace steelmaking process still has a high carbon impact because the process still requires a large input of coal (although not coke), which is also sourced from unsustainable fossil fuels.

[0003] A known method for reducing the total amount of fossil fuels used in the steelmaking process is to inject carbonaceous materials derived from biomass. The chemical, physical, and mechanical properties of raw biomass make it inefficient for use in the steel industry, except by gasifying it to produce reducing gases before injection into the furnace.

[0004] One such method is the method disclosed in Chinese Patent Application CN 114774599, which uses biomass in the form of processed charcoal powder and injects it into the blast furnace through the tuyere together with the main hot air. In this embodiment, "biomass hydrogen-rich micropowder" that is dehydrated, deoxygenated, and hydrogenated is prepared through a "coking-like" process of flash evaporation and pyrolysis of charcoal to produce carbon-rich powder. Subsequently, the powder is injected into the tuyere together with a carbon dioxide transport gas selected to maintain the reduction potential in the furnace, and then the pretreated volatile powder is ignited in the raceway zone.

[0005] The charcoal conversion behavior under the conditions simulating the blast furnace raceway is comparable to, or even better than, that of PCI. Especially at high injection rates, the charcoal conversion behavior becomes more favorable due to partial compensation of oxygen in the blast by the macropores of the charcoal.

[0006] Using biomass in this regard requires extensive pretreatment of biomass materials such as charcoal to improve their energy density and product quality to meet the requirements of blast furnace injection. In addition, although biomass can be used in this regard to directly replace pulverized coal injection, the pretreatment still requires a large amount of heat energy (usually sourced from fossil fuel sources) to allow self-ignition in the raceway zone.

[0007] In addition, although the pretreatment of biomass promotes the improvement of blast-furnace-based steelmaking, including but not limited to higher carbon content, calorific value, apparent density, lower oxygen content, and better grindability, the pretreatment of biomass significantly impairs the solid iron product yield.

[0008] Given the above, it is clear that a careful balance must be achieved among the above aspects, that is, when considering biomass injection, the solid product yield results in a loss of blast furnace operating efficiency, and vice versa. If biomass addition is to be widely adopted, then another heat source is needed to improve the efficiency and sustainability of biomass or charcoal preparation before its combustion to form reducing gases.

[0009] Hydrogen is the most climate-friendly fuel with the highest energy content per unit mass among all fuels. In addition, green hydrogen is regarded as a carbon-free fuel because it is sourced from water electrolysis powered by renewable energy generation. Hydrogen is a strong reducing agent and has strong flammability and diffusibility. For many industrial sectors, it is considered a promising clean fuel for achieving zero carbon dioxide emissions. The above advantages make hydrogen an excellent substitute for carbon-based raw materials in many carbon-intensive industries, including iron and steelmaking.

[0010] The use of hydrogen in blast furnaces has been regarded as a future substitute for carbon-based fuels, including coke and / or pulverized coal, to provide heat energy for the ignition of carbon additives and reduce the total carbon dioxide emissions in blast-furnace steelmaking.

[0011] In Liu, Yiran; Hu, Zhongjie and Shen, Yansong; "CFD Study of Hydrogen Injection in Blast Furnaces: Tuyere Co-injection of Hydrogen and Coal"; Metallurgical and Materials Transactions B, 52B, pp. 2971-2991, two main types of hydrogen metallurgy in the prior art were identified. These types include injecting hydrogen into the blast furnace through tuyere injection to replace coal and coke (Scenario 1: co-injecting hydrogen / coal through the tuyere; Scenario 2: fully injecting hydrogen through the tuyere); or directly injecting the said materials / gases into the furnace. Tuyere injection is considered the most feasible in the art because it only requires minor modifications to the blast furnace and its operation, that is, providing consumable lances for transporting and injecting hydrogen and coal through independent fluid channels.

[0012] Hydrogen / coal co-injection is considered a technology for the transition to all-hydrogen steelmaking. In this regard, the exothermic nature of coal combustion means that its injection compensates for the heat / heat loss experienced by the endothermic hydrogen reactions in the blast furnace. Additionally, this compensatory nature allows for the injection of sufficient reaction heat and reducing materials into the furnace, rather than relying solely on an unstable and expensive hydrogen supply. Overall, coal-hydrogen co-injection is the best-known and most commonly used method in the art for balancing carbon dioxide emissions reduction, reaction kinetics, and operating costs.

[0013] However, considering the rapidly emerging demand for decarbonization in key industries due to global climate change, hydrogen-coal co-injection is still insufficient. According to data from the WMO (World Meteorological Organization), the concentration of greenhouse gases in the atmosphere reached 400 ppm in 2015 and exceeded 413 ppm by 2020. To stabilize the concentration of greenhouse gases at the recognized critical threshold of 450 ppm, a rapid transition to all-hydrogen steelmaking is needed, thereby reducing the addition of coke and / or coal.

[0014] Furthermore, the fundamental problem associated with the widespread use of hydrogen in industrial applications, including steelmaking, is that in the vast majority of cases, the production of hydrogen is "black," i.e., hydrogen is derived from hydrocarbons from fossil fuel sources rather than "green" hydrogen from renewable sources such as water electrolysis. Therefore, there is a need in the art for a solution to provide an intermediate technology and / or method for transitioning to the incorporation of hydrogen in a conventional blast furnace without significant or costly modifications.

[0015] In view of the above problems, such an intermediate technology should combine the cost efficiency and reaction kinetics of hydrogen-coal co-injection while reducing or mitigating the use of fossil fuels to enhance sustainability. Accordingly, an object of the present invention is to overcome or mitigate at least one disadvantage of the prior art or to provide a useful alternative, preferably a method for economic blast furnace steelmaking that provides a useful intermediate technological step for a complete hydrogenation transition while significantly reducing the use of fossil fuels and carbon intensity.

[0016] Any discussion of the prior art throughout the specification should not be taken as an admission that such prior art is well-known or constitutes part of the common general knowledge in the art. Summary of the Invention

[0017] In a first aspect of the present invention, there is provided a steelmaking method, comprising:

[0018] a. Injecting a non-carbon or carbon-neutral fuel comprising at least one combustible gas and a solid carbonaceous material into a tuyere;

[0019] b. Burning at least a portion of the at least one combustible gas;

[0020] c. Blowing the non-carbon or carbon-neutral fuel, including the combustion products of the at least one combustible gas, into the furnace with a blast air stream so that the fuel contacts the burden; and

[0021] d. Reducing the blast furnace burden together with the solid carbonaceous material to produce slag and molten steel,

[0022] wherein the at least one combustible gas and the solid carbonaceous material are co-injected into the tuyere through a lance fluidly connected to the tuyere, and the lance includes a first channel and a second channel adapted to allow the solid and the gas to flow to their adjacent outlets fluidly connected to the tuyere, respectively.

[0023] The at least one combustible gas is an essential co-injection for generating and providing heat energy, which is used to devolatilize the solid carbonaceous material to finally burn in the raceway and thereby in-situ generate reducing gases, such as carbon dioxide and carbon monoxide, for iron reduction. Of course, the combustion of the gas in the exothermic reaction also supplements the heat energy inside the blast furnace and is particularly useful in supporting the overall endothermic reaction kinetics of iron reduction. In addition, the large heat input provided by the exothermic combustion is beneficial to supporting the heat and flow dynamics in the cohesive zone, liquid zone, and hearth zone of the furnace shaft.

[0024] Therefore, the at least one combustible gas is selected based on the combustion kinetics, thermodynamics, autoignition temperature, and ease of source and / or handling of the combustible gas. In this regard, in some embodiments, the at least one combustible gas includes hydrogen. This may include hydrogen gas, hydrocarbon gases, such as methane, propane, and butane, or mixtures thereof, including gas mixtures, such as syngas.

[0025] In another embodiment, the at least one combustible gas includes hydrogen. For this embodiment, the gas stream of the at least one combustible gas is not limited to hydrogen and may also include non-combustible carrier gases, such as nitrogen, air, and / or argon. Preferably, the at least one combustible gas includes hydrogen (H2) at a concentration of 1 to 100% by volume. Preferably, hydrogen accounts for at least 20% by volume. In another embodiment, hydrogen accounts for approximately 20% by volume and nitrogen accounts for approximately 80% by volume.

[0026] The at least one combustible gas is adapted to burn upon contact with a blast air stream (heated to about 1150 to 1350 °C) in a tuyere such that a flame can be maintained at the tip of a lance communicating with the tuyere. In this regard, the at least one combustible gas is selected such that its autoignition temperature is lower than the temperature of the hot blast but higher than the actual temperature range injected into the blast furnace. In this regard, hydrogen is a viable option as it autoignites in the presence of oxygen at temperatures of 585 °C and above, meaning that its combustion flame in the presence of a hot air stream is self-sustaining and relatively easy to maintain.

[0027] Solid carbonaceous materials comprising non-carbon or carbon-neutral fuels refer to solid combustible materials that are not derived from fossil fuel sources and / or require less pretreatment before injection into a blast furnace compared to existing carbonaceous materials including coke, pulverized coal, and / or briquettes. In some embodiments, the solid carbonaceous material is derived from a sustainable source, such as an organic source. Thus, in some embodiments, the solid carbonaceous material is an organic material.

[0028] More preferably, the solid carbonaceous material is biomass, which is generally considered in the art to be derived from plant-based materials such as wood, wood residues, agricultural residues, and waste from industry, farms, and households. In particular, biomass products such as charcoal (biochar in this case) or ash are preferred for injection into the blast furnace. In some examples with similar calorific values, biochar can replace part of the coke at a substitution ratio of 1:1, while dried biomass materials (another form of treated biomass) - can produce a coke replacement ratio of 0.4:1 upon injection through the tuyere.

[0029] In this regard, the biochar used in the preferred embodiments described provides a calorific value of at least 18 MJ / kg, similar to coke particles. Additionally, the biomass particles can be crushed and / or ground to an average diameter of up to 300 μm, with a maximum diameter of 500 μm - a size similar to that of pulverized coal or coke particles in the dead zone of the hearth adjacent to the raceway. In combination with a biomass density of at least 500 kg / m 3 this provides a gas permeability and liquid permeability similar to that of crushed coke particles in the lower section of the furnace, particularly in the liquid zone and the dead zone.

[0030] As in known methods of pulverized coal injection and co-injection of hydrogen and coal, the proposed invention attempts to inject carbonaceous materials, which include biomass materials such as charcoal and torrefied biomass, by entraining them in a conveying gas. Carbonaceous solids in various forms, including but not limited to pellets and crushed particles, are entrained and injected by a stream of an inert conveying gas such as nitrogen, air, and carbon dioxide. The mass flow rate of the conveying gas is adjusted according to the operating properties of the conveying gas to ensure effective entrainment and solid-carrying capacity. In one embodiment, the mass flow rate of the conveying gas is set to be proportional to the desired solid injection rate - approximately 3 to 4% by mass.

[0031] Therefore, those skilled in the art should understand that the biochar has favorable thermal and flow characteristics after being injected into the furnace, such that only minor modifications to the equipment or operating conditions are required to enable carbon injection through the tuyere.

[0032] In embodiments where the hydrogen contains at least one combustible gas, a flame front temperature of 500 - 2000 °C is desirable for the devolatilization and gasification of the solid carbonaceous materials. If biomass materials, especially biochar or ash, are used, then a flame front of 600 to 1600 °C is desired at a distance of 0.05 to 0.3 meters from the tip of the lance, in order to rapidly carry out devolatilization and gasification before the biomass material itself burns in the raceway zone.

[0033] The heat input from the combustion of the devolatilized and gasified biomass results in an adiabatic flame temperature (RAFT) in the raceway zone of the tuyere of 1900 to 2300 °C. This results in a temperature of the top gas escaping from the furnace of approximately 95 to 200 °C - typical operating temperatures for blast furnace operations injecting coke or pulverized coal.

[0034] In another aspect of the present invention, there is provided a system for injecting a non-carbon or carbon-neutral fuel into a steelmaking furnace, the system comprising:

[0035] A lance comprising a first channel adapted for the flow of solid carbonaceous materials and a second channel adapted for the flow of at least one combustible gas;

[0036] Orifices of the first channel and the second channel, the orifices forming a lance tip in fluid communication with the tuyere for co-injecting the solid carbonaceous material and the combustible gas into the blast air stream; and

[0037] A tuyere for injecting the non-carbon or carbon-neutral fuel and the blast air stream into the furnace such that the fuel contacts the burden in the raceway zone,

[0038] wherein the lance and the lance tip are adapted to burn the at least one combustible gas in the presence of the blast air stream.

[0039] In one embodiment, the combustion heats the solid carbonaceous material to assist in devolatilization prior to injection into the raceway of the furnace.

[0040] Equipment known for co-injecting the at least one combustible gas and the solid carbonaceous material affects key operating parameters of blast furnace steelmaking based on injection (e.g., PCI steelmaking), namely, injection velocity, injection flow rate, flame front size, and raceway temperature. One such factor affecting the economy and robustness of the present invention is the design of the lance for injecting the non-carbon or carbon-neutral fuel and the manner of its use.

[0041] In known methods of co-injecting coal and hydrogen into the tuyere, both single-lance methods and dual-lance methods are common. The former embodiment utilizes a single lance including two channels for separately flowing the at least one combustible gas and the solid carbonaceous fuel, with its reservoir in fluid communication with the tuyere through the injection fluid. In contrast, the dual-lance scheme uses a single lance for each of the combustible gas and the carbonaceous solid. Any one of the schemes has some advantages, including ease of identifying problems and replacing the dual lance, and improvement in coal combustion achieved by the proximity of hydrogen combustion to coal feeding in the single-lance scheme.

[0042] The present invention utilizes a single-lance scheme in which a lance including two independent fluid channels is disposed through the tuyere such that the orifices of the lance are adapted to inject the combustible gas and the carbonaceous solid into the blast air stream before or near the tuyere nozzle leading into the furnace. To maximize mixing of the injected materials and thus achieve devolatilization, gasification, and burnout of the carbonaceous solid, certain embodiments of the system place the lance nozzle at the center of the tuyere cross-section, thereby placing the fluid channel orifices at the center of the tuyere cross-section.

[0043] In another embodiment of the lance used in the present invention, an inner annular wall and an outer annular wall are provided extending along its length such that the first channel is formed within the inner annular wall and the second channel is formed between the inner annular wall and the outer annular wall. The arrangement of the walls causes the first channel to form a tubular fluid channel surrounded by the annular second fluid channel. In some embodiments, the inner wall, the outer wall, and the first and second channels formed thereby may be coaxially arranged.

[0044] In a preferred method using a coaxially or non-coaxially arranged lance, the at least one combustible gas flows through the second channel formed between the inner annular wall and the outer annular wall extending along the length of the lance, and the solid carbonaceous material flows through the first channel formed within the inner annular wall.

[0045] A major benefit of specifically selecting hydrogen and flowing it through the second channel is the ability to achieve lance cooling during co-injection operations. According to typical hydrogen injection steelmaking methods known in the prior art, the proposed invention utilizes a combustible gas containing hydrogen, which is injected into the tuyere at its auto-ignition temperature of approximately 25°C to 585°C. Considering that the hot blast air stream is typically preheated to approximately 1150 - 1350°C, there is a significant temperature difference between the tip of the lance exposed to the hot blast air stream and the flowing hydrogen stream to be heated. Therefore, there is a significant thermal driving force to convectively transfer heat from the lance wall to the flowing hydrogen - resulting in significant cooling of the lance tip exposed within the tuyere.

[0046] In addition, the thermal conductivity and specific heat capacity of the lance material and hydrogen respectively affect this lance cooling effect. In particular, hydrogen has a very high specific heat capacity, which represents the convective heat removal capacity of hydrogen flowing through the second channel for each degree increase in temperature. Therefore, the increase in hydrogen temperature caused by the contact of hydrogen with the heated metal lance tip, mixing with the hot blast air stream, and subsequent ignition near the lance orifice makes hydrogen very suitable for removing heat from the lance and alleviating or preventing temperature-related degradation of the lance.

[0047] The lance used in these embodiments is designed such that this lance cooling effect occurs through the convection of a subsonic combustible gas stream. The total cross-sectional area of each lance and the cross-sectional areas of the two channels therein are sized such that this lance cooling can be achieved in each lance at a full furnace co-injection rate of up to 35 kg of combustible gas / ton of hot metal (kg / tHM) and up to 250 kg / tHM of carbonaceous solids injected through the lance-tuyere device.

[0048] This lance cooling effect is effective whether the hydrogen flows through the internal tubular channel or the external annular channel. However, those skilled in the art should understand that by flowing the hydrogen through the external annular second channel, the cooling effect on the outer wall of the lance can be maximized, and thus thermal damage to it can be alleviated.

[0049] The above-mentioned lance cooling effect aims to reduce or prevent temperature-related degradation of the lance, especially the lance tip. Consumable lances are known in the prior art for coal injection or hydrogen - coal co-injection blast furnaces, and such consumable lances are easily replaced when the lance tip deteriorates due to relatively short to medium-term high-temperature exposure in the tuyere. The continuous lance cooling effect brought about by the subsonic flow of the combustible gas containing hydrogen allows such lances to be effectively reused - allowing for a longer service life and preventing costly maintenance or furnace shutdown times for lance replacement.

[0050] As described above, the co-injected combustible material ignites when injected into the tuyere and comes into contact with the hot blast air stream, thereby forming a high-temperature flame front. In the present invention, the blast air stream through the blowpipe is rich in oxygen to promote the above combustion reaction and also provide sufficient oxygen for the standard blast furnace coke oxidation and iron reduction reactions. In one example, the blast gas is rich in oxygen in a stoichiometric proportion required for complete combustion of the combustible gas.

[0051] For example, in the case where the at least one combustible gas comprises a mixture of nitrogen and hydrogen in a volume percentage of approximately 80:20, the oxygen component of the blast air stream is also increased to as high as 40 volume percentage to accommodate the additional combustion of hydrogen.

[0052] As described above, the combustion of the combustible gas including hydrogen produces a significantly deoxygenated flame front with extremely high temperature (about 1200 to 1600 °C) in the tuyere, and this flame front extends from the tip of the lance. The exposure of the co-injected solid carbonaceous materials such as biomass leads to devolatilization. Subsequently, pyrolysis occurs, from which volatile substances are released, such as light permanent gases (including H2, CO, CO2, CH4, H2O, NH3) and tar (e.g., condensable hydrocarbon vapors), leaving the char solids with volatiles removed.

[0053] Without wishing to be bound by the theory of models of the reaction mechanism in the blast furnace being built, the in-situ devolatilization reaction related to the biomass material, for example, can be represented by a competing model, each model being represented by the following chemical equations 1 and 2:

[0054]

[0055] Both of the above two equations represent a part (α) of the originally injected biomass, i.e., the volatile matter (VM) separated from the char material that has been devolatilized and is rich in carbon at a rate determined by the reaction rate constant Kv. Both Kv constants are exponentially related to temperature. Thus, at the above high flame front temperature and in the presence of a hot blast air stream, the devolatilization reaction plays an important role in preparing the coked carbonaceous solid for combustion or gasification.

[0056] In addition, the fact that the devolatilization reaction is exponentially related to temperature means that providing a high-temperature heat source in the form of combustion gas near the tip of the lance results in effective catalysis of the in-situ devolatilization. Therefore, in some embodiments, the rate of devolatilization of the solid carbonaceous material substantially depends on the combustion of the at least one combustible gas.

[0057] For embodiments utilizing biomass, this in-situ devolatilization reaction stands in direct contrast to existing blast furnace steelmaking with injected biomass, which pre-treats the biomass before injecting it into the tuyeres or the furnace. Compared to the expensive, energy-consuming, and cumbersome existing processes required in the latter existing scenario, the in-situ devolatilization driven by the combustion of co-injected hydrogen is both efficient and effective.

[0058] In fact, the increased temperature of the carbonaceous solids near the high-temperature flame front means that a greater portion of the injected particles devolatilize and burn out in the raceway. This directly leads to earlier and greater production of the conventional blast furnace gases, such as carbon monoxide and carbon dioxide, used to reduce the iron ore charged into the furnace. Additionally, by effectively catalyzing the devolatilization and subsequent combustion of the coked solids, the injection of hydrogen together with the biomass makes the latter's injection more efficient and practical.

[0059] Once injected into the furnace, the carbonaceous material "burns out" by means of temperature-driven chemical consumption of its carbon-rich and devolatilized solids to form reducing solids. This chemical consumption occurs mainly through two routes within the blast furnace, namely, oxidation and gasification. Without wishing to be bound by the theory behind the precise chemical kinetic models established for the blast furnace, the reactions supporting the competing models of biomass oxidation and gasification can each be represented by the following equations:

[0060]

[0061] Due to the use of a heated oxygen-enriched blast air stream, the main mode of carbon consumption in the blast furnace is oxidation. As shown by one such reaction process exemplified in Equation 3 above, the oxygen supplied in the hot blast air stream reacts with the carbon-rich coke to produce a stoichiometric mixture of the reducing agents carbon monoxide and carbon dioxide. Both of these reducing agents are active reducing agents within the blast furnace and can be used to reduce iron oxides to form pig iron or steel.

[0062] The other two routes involve relatively direct gasification reactions, which occur only under high-temperature conditions, such as in the hydrogen flame front or the blast raceway. In this regard, the reactants with which the devolatilized carbonaceous solids react are all possible combustion products of fuel combustion, namely, carbon dioxide (CO2) and water (H2O). In this regard, at least one combustible gas can be selected such that its combustion products gasify at least a portion of the solid carbonaceous material in the raceway. As exemplified by Equations 4 and 5, it is clear that the combustion of combustible gases such as methane and hydrogen at the lance tip subsequently promotes gasification and the production of reducing gases for steelmaking.

[0063] For the latter water-based gasification reaction, such as the reaction disclosed in Equation 5, the production of hydrogen (H2) means that it is possible for the products of the further exothermic combustion of the reaction to reform into water molecules - as long as there is a stoichiometrically sufficient amount of oxygen and heat retained in the furnace. Therefore, it is preferred to further carry out the chain reactions of hydrogen-based gasification and water recombination along the raceway and further into the furnace hearth, and this can be promoted by the co-injection of hydrogen-containing gas and biomass material.

[0064] This chain effect caused by the co-injection of hydrogen through the lance promotes the direct combustion and devolatilization of the biomass, spreads the heat energy and carbon consumption, and increases the heat available for further reduction in the furnace. This synergistic effect improves the process efficiency, improves the carbon burnout, and increases the carbon utilization rate of the blast furnace.

[0065] Accordingly, in another aspect of the present invention, there is also provided a method of using the system disclosed herein, the method comprising the following steps:

[0066] a. Passing the solid carbonaceous material and the at least one combustible gas through the first channel and the second channel of the lance;

[0067] b. Injecting the solid carbonaceous material and the at least one combustible gas into the blast air stream through the adjacent outlets of the first channel and the second channel;

[0068] c. Burning at least a portion of the at least one combustible gas in the presence of the blast air stream;

[0069] d. Devolatilizing at least a portion of the solid carbonaceous material with the heat generated by the combustion;

[0070] e. Blowing the at least one combustible gas, its combustion products, and the carbonaceous material into the blast furnace and bringing the burden into contact with them in the raceway; and

[0071] f. Reducing the burden to produce molten steel and slag.

[0072] Definitions

[0073] In describing and claiming the scope of the present invention, the following terms will be used according to the definitions given below. It should also be understood that the terms used herein are for the purpose of describing particular embodiments of the present invention only and are not restrictive. Unless otherwise defined, all technical and scientific terms used herein have the meanings commonly understood by those of ordinary skill in the art to which the present invention pertains.

[0074] Except as otherwise expressly required by the context, throughout the specification and claims, the word "comprising" and its grammatical variations shall be construed to have an inclusive meaning rather than an exclusive or exhaustive meaning; that is, the meaning of "including but not limited to".

[0075] The phrase "consisting of" as used herein excludes any element, step, or ingredient not specified in the claim. When the phrase "consisting of" (or its variations) appears in a clause of the body of a claim rather than immediately following the preamble, it limits only the elements listed in that clause; it does not exclude other elements of the overall claim. The phrase "consisting essentially of" as used herein limits the scope of a claim to the specified elements or method steps plus elements or method steps that do not materially affect the basic and novel characteristics of the claimed subject matter.

[0076] Regarding the terms "comprising", "consisting of", and "consisting essentially of", when one of these three terms is used herein, the subject matter disclosed and claimed herein may include the use of any one of the other two terms. Thus, in some embodiments not explicitly recited, any instance of "comprising" may be replaced with "consisting of" or "consisting essentially of".

[0077] Except as otherwise indicated in the operating examples or otherwise shown, all numbers expressing quantities of ingredients or reaction conditions used herein shall be understood to be modified in all instances by the term "about". These examples are not intended to limit the scope of the invention. Hereinafter, unless otherwise indicated, "%" means "% by volume", "proportion" means "volume ratio", and "parts" means "parts by volume".

[0078] Except as otherwise indicated, the term "substantially" as used herein shall mean, depending on the context in which it is used, containing more than 50% by volume, mass, or weight. Preferably, this means more than 75%. More preferably, this means more than 90%. Most preferably, this means 100% or close to 100%.

[0079] The recitation of numerical ranges by endpoints includes all numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

[0080] The terms "preferred" and "preferably" refer to embodiments of the invention that can provide certain benefits in certain circumstances. However, in the same or other circumstances, other embodiments may also be preferred. Moreover, the recitation of one or more preferred embodiments is not meant to imply that other embodiments are not useful, nor is it intended to exclude other embodiments from the scope of the invention.

[0081] It should also be noted that, unless the context clearly requires otherwise, the singular forms "a", "an", and "the" as used in the specification and the appended claims include plural referents.

[0082] The prior art mentioned herein is incorporated herein by reference.

[0083] Although exemplary embodiments of the disclosed technology have been described in detail herein, it should be understood that other embodiments are also contemplated. Accordingly, the scope of the disclosed technology is not limited to the details of the construction and arrangement of the components set forth in the following description or shown in the drawings. The disclosed technology may have other embodiments and can be practiced or implemented in various ways. BRIEF DESCRIPTION OF THE DRAWINGS

[0084] The present invention will now be described by way of example with reference to the accompanying drawings, in which:

[0085] Figure 1a is a schematic cross-sectional view of a blast furnace according to the present invention, including a tuyere and a lance for co-injecting solid carbonaceous material and combustible gas; Figure 1b is an enlarged schematic view of the tuyere including the co-injection lance; Figure 1c is a front projection of a cross-section of the lance, showing coaxial annular fluid channels for co-injection;

[0086] Figure 2a is an enlarged cross-sectional view of the specific heat capacity contour lines of co-injected nitrogen and biomass material in the tuyere; Figure 2b is an enlarged cross-sectional view of the specific heat capacity contour lines of co-injected hydrogen and biomass material in the tuyere;

[0087] Figure 3a and Figure 3b are enlarged isothermal cross-sectional views of air and hydrogen-nitrogen mixture co-injected into the furnace through the tuyere together with biomass particles, respectively;

[0088] Figure 4a and Figure 4b are schematic diagrams of biomass consumption and particle temperature plotted against the distance from the tip of the lance, respectively;

[0089] Figure 5a and Figure 5b are enlarged isothermal cross-sectional views of air and hydrogen co-injected into the tuyere from the lance together with biomass particles, respectively;

[0090] Figure 6 is a schematic diagram of distance-dependent biomass particle consumption in the tuyere and the raceway of the furnace;

[0091] Figure 7a and Figure 7bMagnified cross-sectional views of the mole fraction contours of water molecules along the tuyere and the furnace raceway in the cases of co-injection of air and hydrogen with biomass, respectively; and

[0092] Figure 8a and 8b is a magnified cross-sectional view of the path taken by hydrogen molecules released from the co-injected biomass. Detailed implementation manners

[0093] Those skilled in the art should understand that the present invention includes the embodiments and features disclosed herein, as well as all combinations and / or permutations of the disclosed embodiments and features.

[0094] Example 1 - Tuyere gun and structure

[0095] Referring to Figure 1a , which shows the internal structure of blast furnace 100 taken along the symmetry plane. The blast furnace 100 includes a tuyere 101 that is in fluid communication with a blowpipe 102 and an injection lance 103. The tuyere 101 is adapted to inject a hot blast air stream into the raceway region 104 of the blast furnace, thereby forming a raceway 105 adjacent to the dead zone 106. The injected blast air stream also contains solid carbonaceous materials and at least one combustible gas co-injected into it by the lance 103. The combustion of the at least one combustible gas in the tuyere 101 and subsequent devolatilization of the solid carbonaceous materials result in the gasification and / or reduction of the devolatilized carbon-containing solids in the raceway 105.

[0096] The resulting reducing gas (a mixture of carbon oxides and hydrogen) 107 rises through the furnace 100 and combines with a similar gas produced by the carbon oxidation of the coke layer 108 to reduce the iron ore charged in the iron ore layer 109. The remaining reducing gas escapes from the furnace in the form of top gas, while the solid charges of coke and iron ore sink in a countercurrent manner towards the softening zone 110 and the dead zone 106 in the lower section of the furnace 100. After passing through the coke particles in the dead zone 106, the reduced iron ore separates to form a liquid slag layer 111 and a hot metal layer 112 at the bottom of the furnace 100.

[0097] Referring to Figure 1b , the lance 103 is tangentially and properly placed in a sleeve 113 adjacent to the tuyere cooler 114, which includes a blowpipe 102. The lance 103 and the blowpipe 102 are in fluid communication with the tuyere 101 that penetrates the blast furnace wall. The tip 115 of the lance 103 extends into the center of the cross-section of the tuyere, such that the contact / entrainment of the co-injected material with the blast air stream is maximized. The tuyere 101 includes a tuyere orifice 116 facing the internal volume of the blast furnace, so that it enables molten iron ore and coke to be in fluid communication with the oxygen-rich blast.

[0098] The lance 103 is adapted to promote the combustion of the at least one combustible gas at its tip 115 and form a flame front adjacent thereto in the tuyere 101 for devolatilizing the solid carbonaceous material co-injected with the at least one combustible gas. Refer to Figure 1c , the lance 103 includes two coaxial cylindrical walls, namely, an outer wall 117 and an inner wall 118, and the space between the outer wall and the inner wall forms a fluid passage 119 which is adapted for the flow of the at least one combustible gas. Another inner fluid passage 120 is formed within the cylindrical inner wall 118 and is adapted for the flow of the solid carbonaceous material and the conveying gas.

[0099] Example 2 - Lance Cooling

[0100] In another embodiment of the present invention, the at least one combustible gas flows through the outer fluid passage 201 of the lance 200. Refer to Figure 2a , the isotherms of the specific heat capacity of the material flowing through the lance 200a show that the nitrogen co-injected through the outer fluid passage 201a has a slightly higher specific heat capacity compared to the solid combustible material flowing through the orifice of the inner fluid passage 202a of the lance. In contrast, the hydrogen flow through the Figure 2b outer fluid passage 201b of the lance 200b in shows a significant increase in the specific heat capacity in the region inside the passage and adjacent to the orifice of the tip 203a of the lance. In addition, a clear trace of the high specific heat capacity of the hydrogen jet originating from the tip 203b of the lance can be observed, which extends outward along the blowpipe 204b and towards the furnace structure.

[0101] This demonstrates the higher specific heat capacity of hydrogen and the heat removal ability of the gas when used as the at least one combustible gas. In addition, the trajectories of the gas or particles with a higher specific heat capacity compared to the blast air flow show the potential for heat removal from the lance and thus the potential for reducing heat-related damage in the coaxial biomass-hydrogen co-injection lance.

[0102] Example 3 - Hydrogen Combustion and Devolatilization

[0103] Comparison Figure 3a and 3b , the co-injection of air (Case 1) and at least one combustible gas in the form of a hydrogen-nitrogen mixture with 20.9 vol% hydrogen (Case 2) and the biomass material respectively show the potential for combustion and forming a flame front when using the combustible gas. The combustible hydrogen-nitrogen mixture flows at a rate of 1.92 kg / hr, while the biomass carbonaceous material is injected at a rate of 35 kg / hr. The conveying gas flow rate is also set to 3 - 4% of the mass flow rate of the biomass.

[0104] In the embodiment where the hydrogen-nitrogen gas mixture is co-injected with the biomass, at Figure 3bA flame front between 1200 °C and 1600 °C can be observed near the outer fluid passage 301b of the spray gun 300b in []. In contrast, no equivalent flame front was observed in the case of co-injecting air instead of combustible gas Figure 3a No such equivalent flame front was observed. Additionally, when comparing Figure 3a and 3b it can be observed that the thermal distribution of the particle temperature in the tuyere and the furnace is significantly affected by the injection and combustion of hydrogen-containing gas. In particular, a hotter gas and / or particle plume that penetrates deeper into the furnace can be observed.

[0105] In Figure 4a and 4b the effects of hydrogen injection and combustion on biomass burnout and particle temperature can be observed. Referring to the latter figure, for the second case, a continuous increase in particle temperature was observed axially at a distance of 0.05 to 0.3 m from the spray gun tip. This temperature increase is clearly due to the additional thermal energy introduced into the area around the spray gun tip from the exothermic combustion of co-injected hydrogen in the second case. As Figure 4a was observed, the increase in temperature is also associated with an increase in biomass consumption within the same distance range from the spray gun tip. In this regard, the increase in biomass consumption represents an increase in the thermal exposure experienced by the co-injected biomass and the subsequent release of volatile substances from this solid material due to hydrogen combustion.

[0106] When separately comparing the co-injection of air and hydrogen with biomass in Figure 5a and 5b respectively, a hydrogen combustion flame front can also be observed. In this regard, the flame front is clearly visible as a highly localized area of higher temperature. The improved devolatilization of the biomass and subsequent "burnout" can also be observed in the illustration of Figure 6 . In particular, an increase in biomass consumption was observed at a distance of 0.6 to 1.4 m from the spray gun tip. This indicates that hydrogen injection and combustion catalyze the devolatilization process by providing more heat to adjacent biomass particles. The correlation between the heat released by hydrogen combustion and biomass devolatilization that was observed can be described by Equations 1 and 2, where the devolatilization reaction depends only on the reaction rate constant that varies exponentially with temperature.

[0107] Example 4 - Biomass Gasification

[0108] Referring back to Figure 6, when hydrogen instead of air is co-injected with the biomass as at least one combustible gas, a significant improvement in biomass burnout can be observed at a position further away from the lance tip. In this regard, when 4.13 kg H2 / tHM of hydrogen is co-injected with biomass particles, a higher burnout can be observed in the second case (hydrogen co-injection) in the range of 1.70 m to 2.0 m. The increase in burnout occurs at the end of the raceway, which is a typical coke reaction zone.

[0109] The contour lines and particle trajectories of the raceway illustrate the enhanced burnout of biomass particles downstream. Refer to Figure 7a and 7b , in the case of injecting hydrogen at 4.13 kg H2 / tHM, the water vapor content throughout the raceway is significantly higher in the latter (the second case). This indicates that the injected hydrogen is rapidly converted to water once it comes into contact with the oxygen in the tuyere.

[0110] On the other hand, Figure 8a and 8b show the mass flow path of hydrogen molecules released from the biomass plume and entering the raceway. Hydrogen is also a product of coke gasification, as highlighted by Equation 5, and it can be regarded as an important indicator for evaluating the coke gasification rate. A higher intensity of hydrogen released from the biomass plume can be observed in Figure 8b , indicating that a higher concentration of water vapor in the raceway is beneficial to the coke gasification reaction. In short, the co-injection of hydrogen and biomass is beneficial for indirectly enhancing coke burnout by coke gasification with water.

[0111] Those skilled in the art should understand that, in addition to the specific changes and modifications described, other changes and modifications can be easily made to the invention described herein. It should be understood that the invention includes all such changes and modifications that fall within the spirit and scope of the invention.

[0112] Example 5 - Exemplary Parameters of Co-Injection

[0113] In one embodiment of the present invention, hydrogen and biomass are co-injected into a blast furnace with an internal volume of at least 3000 m 3 while operating, using the following operating parameters.

[0114] Table 1 - List of Operating Parameters for Co-Injection of Hydrogen and Biomass

[0115]

[0116] For the co-injection of hydrogen and biomass, the steady-state operation of the blast furnace was achieved under the above parameters. The resulting operating conditions observed in the blast furnace are listed in Table 2. In particular, favorable thermal characteristics were achieved in the raceway while maintaining an iron production rate typical for the size of the blast furnace.

[0117] Table 2 - Observed operating conditions of the blast furnace

[0118]

Claims

1. A steelmaking method, comprising: a. injecting a non-carbon or carbon-neutral fuel comprising at least one combustible gas and a solid carbonaceous material into a tuyere; b. burning at least a portion of the at least one combustible gas; c. blowing the non-carbon or carbon-neutral fuel, including the combustion products of the at least one combustible gas, into the furnace with a blast air stream such that the fuel contacts the burden in a raceway; and d. reducing the blast furnace burden together with the solid carbonaceous material to produce slag and molten steel, wherein the at least one combustible gas and the solid carbonaceous material are co-injected into the tuyere through a lance in fluid communication with the tuyere, the lance comprising a first channel and a second channel, the first channel and the second channel being adapted to allow the solid and the gas to flow to their adjacent outlets in fluid communication with the tuyere respectively.

2. The method according to claim 1, wherein the at least one combustible gas comprises hydrogen.

3. The method according to claim 2, wherein the combustible gas comprises hydrogen gas.

4. The method according to any one of the preceding claims, wherein the solid carbonaceous material is an organic material.

5. The method according to claim 4, wherein the solid carbonaceous material is biomass.

6. The method according to claim 5, wherein the solid carbonaceous material is biochar.

7. The method according to any one of the preceding claims, wherein the at least one combustible gas flows through the second channel formed between an inner annular wall and an outer annular wall extending along the length of the lance, and the solid carbonaceous material flows through the first channel formed within the inner annular wall, wherein the tip of the lance is cooled by a subsonic gas stream of the at least one combustible gas passing through the second channel to mitigate temperature-related deterioration.

8. The method according to claim 7, wherein the inner annular wall and the outer annular wall are coaxial.

9. The method according to claims 7 and 8, wherein the lance is reusable.

10. The method according to any one of the preceding claims, wherein devolatilization of at least a portion of the solid carbonaceous material is assisted by the heat generated by the combustion of the at least one combustible gas.

11. The method according to claim 10, wherein the rate of devolatilization of the solid carbonaceous material depends substantially on the combustion of the at least one combustible gas.

12. The method according to any one of the preceding claims, wherein the at least one combustible gas is selected such that its combustion products gasify at least a portion of the solid carbonaceous material in the raceway.

13. The method according to claim 12, wherein the gasification comprises oxidizing the solid carbonaceous material to produce a reducing agent for reducing the burden.

14. The method according to claims 12 and 13, wherein the at least one combustible gas comprises hydrogen such that its combustion products are water, suitable for generating a reducing gas in the furnace.

15. A lance used in the method according to any one of the preceding claims.

16. A system for injecting a non-carbon or carbon-neutral fuel into a steelmaking furnace, comprising: A lance, said lance comprising a first passage adapted for the flow of solid carbonaceous material and a second passage adapted for the flow of at least one combustible gas; The orifices of said first passage and said second passage, said orifices forming a lance tip in fluid communication with the tuyere for co-injecting said solid carbonaceous material and combustible gas into the blast air stream; and A tuyere, said tuyere for injecting said non-carbon or carbon-neutral fuel together with the blast air stream into said furnace such that said fuel contacts the burden in the raceway; wherein said lance and lance tip are adapted to combust said at least one combustible gas in the presence of said blast air stream.

17. The system according to claim 16, wherein said combustion heats said solid carbonaceous material to assist in devolatilization thereof prior to injection into said furnace raceway.

18. The system according to claim 16 or claim 17, wherein said at least one combustible gas comprises hydrogen.

19. The system according to any one of claims 16 to 18, wherein said solid carbonaceous material is biomass or biochar.

20. The lance according to any one of claims 16 to 19, comprising an inner annular wall and an outer annular wall extending coaxially along its length such that said first passage is formed within said inner annular wall and said second passage is formed between said inner annular wall and said outer annular wall; wherein said lance tip is cooled by a subsonic gas stream of said at least one combustible gas passing through said second passage to mitigate temperature-related degradation.

21. The lance according to claim 20, wherein said lance is reusable.

22. The system according to any one of claims 16 to 21, wherein said tuyere is adapted to inject the combustion products of said at least one combustible gas such that said devolatilized solid carbonaceous material is gasified in said raceway.

23. A method of using the system according to any one of claims 16 to 22, comprising the steps of: a. Passing said solid carbonaceous material and said at least one combustible gas through said first passage and second passage of said lance; b. Injecting said solid carbonaceous material and said at least one combustible gas into said blast air stream through adjacent outlets of said first passage and second passage; c. Combusting at least a portion of said at least one combustible gas in the presence of said blast air stream; d. Devolatilizing at least a portion of said solid carbonaceous material with the heat generated by said combustion; e. Blowing said at least one combustible gas, its combustion products and said carbonaceous material into said blast furnace and bringing said burden into contact therewith in the raceway; and f. Reducing said burden to produce molten steel and slag.

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