Tuyere and method for operating a blast furnace with reduced coke consumption by controlled injection of one or more solid, liquid, or gaseous fuels

Abstract

The present invention relates to a tuyere for injecting hot air into a blast furnace. The tuyere comprises three injection lances. A first injection lance and a second injection lance are used for the injection of solid and / or liquid fuels, and a third injection lance is used for the injection of a gaseous fuel. The longitudinal axes and discharge ends of the first and second injection lances are configured to deliver said solid and / or liquid fuels at predetermined angles relative to the longitudinal axis of the tuyere, in order to increase turbulence and improve the mixing of the solid and / or liquid fuels. The discharge ends of the first and second injection lances are located inside the bosh, closer to the furnace burden than to the tuyere. The discharge end of the third injection lance is positioned in the bosh at a selected distance from the discharge ends of the first and / or second injection lances, according to the combustion properties of the solid and / or liquid fuels, forming a high-temperature zone in the vicinity of the discharge ends of the first and second injection lances. The injection rate of each of the fuels is controlled such that solution loss is less than 29%. The injection of light liquid and gaseous hydrocarbons and CO₂-neutral liquid or gaseous biofuels, such as biodiesel or bioethanol, contributes to reducing fossil CO₂ emissions, thus reducing the carbon footprint of the blast furnace.

Description

ALGARAVIZ AND OPERATING METHOD OF A BLAST FURNACE WITH REDUCED COKE CONSUMPTION BY MEANS OF CONTROLLED INJECTION OF ONE OR MORE SOLID, LIQUID OR GASEOUS FUELS Field of Invention

[0001] The present invention relates to a blast furnace tuyer and a method of operating a blast furnace, configured to allow the flexible, selective, simultaneous or separate injection of various solid, liquid or gaseous fuels into the interior of a blast furnace, by means of at least one of its hot air tuyeres, with the aim of reducing coke consumption. More specifically, the invention relates to a blast furnace tuyer configured to contain three injection lances, intended for the selective introduction, into the hot air flow blown by said tuyeres, of one or more fossil and / or non-fossil fuels, in solid, liquid or gaseous state, each lance having a fuel discharge end positioned outside the tuyere and inside the tuyere, so as to allow efficient combustion of the injected fuels.The injection of solid, liquid, and gaseous hydrocarbons, as well as CO2-neutral liquid or gaseous biofuels such as biodiesel or bioethanol, contributes to the reduction of CO2 emissions from the blast furnace. Background of the Invention

[0002] In recent years, growing global concern about rising carbon dioxide emissions and their impact on global warming has prompted a critical analysis of industrial processes, including the steel industry. Reducing the carbon footprint in steel production has become a priority. Blast furnace operations have been a focal point for mitigating carbon emissions, with specific emphasis on reducing the Reduction Agent Ratio. (RAR), in order to minimize environmental impact.

[0003] Traditionally, blast furnaces use coke and pulverized coal as the main reducing agents. However, the need to reduce the consumption of fossil-based reducing agents has driven the search for alternative materials, such as natural gas and CO2-neutral liquid or gaseous biofuels. Replacing traditional fossil reducing agents and consequently reducing the coke rate aims to decrease emissions in the steelmaking process. The simultaneous injection of gaseous or liquid fuels and pulverized coal improves combustibility and allows for greater utilization of these inputs.

[0004] With the aim of reducing the coking rate, blast furnace operators have proposed replacing coke with non-coking coals, which can be used to provide energy for iron ore reduction and metallic iron smelting, but not to form the structure of the solid material bed inside the blast furnace.

[0005] Pulverized coal injection (PCI) via blast tubes and tuyeres that conduct hot air has been practiced for years, with the pulverized coal being carried by an air current through a single lance that delivers it to a position in the tuyeres or tuyeres, where the coal is devolatilized, heated, and burned. Since the combustion of pulverized coal with oxygen generates a high-temperature flame, in the range of 2000 °C to 2500 °C, various lance and blast tube configurations have been proposed with the aim of achieving high coal combustion efficiency while also protecting the blast tubes, injection lances, and tuyeres.

[0006] Japanese patent JP 2007162038 describes a method for injecting reducing agents into a blast furnace tuyere, using one lance for injecting pulverized coal and a separate lance for injecting a gaseous reducing agent (city gas). The city gas injection point is defined within a range of 0 to 150 mm downstream from the pulverized coal injection point, i.e., in a region where oxygen is consumed by the ignition and combustion of the pulverized coal and the oxygen concentration is reduced. This patent mentions that if the pulverized coal injection orifice (port 7a) is positioned more than 150 mm outside the furnace relative to the gaseous reducing agent injection orifice (port 5a), pressure drop problems may occur in the furnace, due to the increased gas volume caused by the combustion of the gas inside the furnace (as illustrated in Figures 3 and 4). The purpose of the city gas injection is to use it as an additional reducing agent to the pulverized coal and a synthetic resin material.

[0007] U.S. Patent No. 9,309,578 describes a method of operating a blast furnace by injecting at least one solid reducing material using a lance formed by a bundle of blow tubes arranged side-by-side and housed in a main tube. The three-tube lance allows the injection of pulverized coke and oxygen or enriched air, promoting better coal combustion. The discharge ends of the three injection lances are arranged close to each other so that the injection paths of the fuels and oxygen are parallel to each other.

[0008] The combustion efficiency of pulverized coal is increased by injecting oxygen precisely at the point of pulverized coal injection. A flammable fuel, such as liquefied natural gas (LNG), is injected through a separate lance. The end of the lance that injects the flammable reducing agent is positioned closer to the furnace inlet, at a distance greater than 0 to 50 mm from the lance that injects the solid reducing agent.

[0009] This patent teaches that when solid reducing material, gaseous reducing material, and additional oxygen are simultaneously injected into the furnace via a beam-type lance, the process demonstrates that... In the case of pipes, the front end of the valve for the gaseous reducing material should be positioned at a distance of 0 to 100 or 200 mm upstream from the front end of the valve for the solid reducing material, in order to improve combustibility.

[0010] U.S. Patent No. 9,410,218 describes a method of operating a blast furnace comprising two or more injection lances for introducing reducing agents, including a solid reducing agent and a flammable reducing agent, through distinct lances. The flammable reducing agent is injected through a single-walled lance, while the end of the double-walled lance that injects pulverized coal is positioned closer to the furnace inlet, in the injection direction, at a distance greater than 0 mm and up to 50 mm from the end of the single-walled lance that injects liquefied natural gas (LNG). Preferably, oxygen-enriched air with a concentration of 50% or more is used as the combustion gas.

[0011] Although the above solutions have represented advances in addressing the challenges related to combustibility, the present invention introduces a new blast furnace nozzle design with three injection lances, which provides not only improved combustion but also better distribution and burning of liquid and gaseous fuels, such as biomass-derived biofuels, contributing significantly to a more sustainable and environmentally responsible metallurgical process.

[0012] The applicants found that an effective and efficient method, as well as an appropriate arrangement of the injection lances in a tuyere and blast furnace, to reduce the coke rate in the operation of a blast furnace, consists of injecting a solid fuel through two injection lances that deliver the fuel inside the tuyere and outside the tuyere, forming a turbulent flow in the hot air, and injecting, through a third lance, a gaseous fuel, such as natural gas, at a point located upstream of the point. solid or liquid fuel injection. Gaseous fuel is injected at a position between 200 mm and 400 mm upstream from the solid or liquid fuel injection position. Objectives of the Invention

[0013] It is therefore an objective of the present invention to provide methods and systems that increase the efficiency and environmental sustainability of blast furnace operations through the controlled injection of solid, liquid and / or gaseous fuels.

[0014] Another objective of the invention is to provide a method of operating a blast furnace with lower CO2 emissions, efficiently replacing fossil coal and coke with solid, liquid or gaseous hydrocarbon fuels, or even biofuels, without causing damage to the environment.

[0015] Yet another objective of the invention is to provide a blast furnace nozzle comprising three injection lances configured for the injection of solid, liquid or gaseous fuels, or biofuels, while maintaining high combustion efficiency of these fuels and stable blast furnace operation.

[0016] Other objectives of the invention will be indicated later or will be evident from the description of the invention. Summary of the Invention

[0017] The objectives of the present invention are generally achieved by providing a nozzle for injecting hot air and solid, liquid, or gaseous fuels into a blast furnace. The nozzle comprises three injection lances, wherein a first injection lance and a second injection lance are used for injecting solid and / or liquid fuels, and a third injection lance is used for injecting a gaseous fuel. The longitudinal shafts and discharge ends of the first and second injection lances are configured to provide the Solid fuels are placed at predetermined angles relative to the longitudinal axis of the nozzle, in order to increase turbulence and improve the mixing of solid and / or liquid fuels with oxygen from the hot air.

[0018] The longitudinal axis and discharge end of the third boom are configured to deliver gaseous and / or liquid fuel at a predetermined angle relative to the longitudinal axis of the boom, increasing the combustion efficiency of the solid fuel.

[0019] The discharge ends of the first and second injection lances are located inside the tuyere, closer to the raceway (formed by the gases generated in the combustion of the fuels in the blast furnace charge) than to the tuyere tank. The discharge end of the third injection lance is positioned in the tuyere at a distance of between 200 mm and 400 mm upstream, relative to the discharge ends of the first and second injection lances. Flow control devices can be provided to regulate the fuel injection rate so that the solution loss is less than 29%.

[0020] The objectives of the invention are also generally achieved by proposing a method of operating a blast furnace in which hot air is blown through a raceway forming the raceway in the cohesive zone of the blast furnace, the raceway comprising three injection lances housed inside it for injecting solid and / or liquid and / or gaseous fuels.

[0021] The method comprises: the injection of a solid fuel by means of a first and a second injection lance, whose discharge ends are configured to deliver the solid fuel at predetermined angles relative to the longitudinal axis of the nozzle, in order to increase turbulence and improve mixing. liquid fuel is mixed with hot air; and a gaseous fuel is injected by means of a third injection nozzle.

[0022] Solid fuel is injected at a first position within the tuyere, closer to the blast furnace charge than to the sluice gate, while gaseous fuel is injected at a second position in the tuyere, located at a distance of between 200 mm and 400 mm from the first position, in order to form a high-temperature flame zone and raise the temperature in the tuyere, increasing the combustion efficiency of solid and / or liquid fuels. The fuel injection rate can be controlled so that the solution loss is less than 29%. Brief Description of the Drawings

[0023] Figure 1 presents a schematic diagram of a general configuration of a blast furnace, illustrating some of the material flows involved in the description of one embodiment of the invention.

[0024] Figure 2 presents a schematic diagram of one embodiment of the invention, showing a blast furnace wall with a tuyere and a nozzle for supplying hot air and oxygen from a hot air distributor, the tuyere having three injection lances.

[0025] Figure 3 presents a schematic diagram of one embodiment of the invention, in perspective view of a nozzle with three injection lances.

[0026] Figure 4 presents a schematic diagram of one embodiment of the invention, showing a view of a blast furnace tuyere with three injection lances, as seen from the end of the tuyere that fits into the blast furnace tuyere.

[0027] Figure 5 presents five schematic diagrams of the injection lance configurations inside the tuyere that were the subject of computer simulations.

[0028] Figure 6 presents a graph in which the amount of natural gas injected is correlated with the percentage of coke replacement and with the loss due to solution loss.

[0029] Figure 7 presents a graph in which the amount of natural gas injected is correlated with the flame temperature generated by the combustion of natural gas and with the amount of additional oxygen in the hot air as a function of the amount of natural gas injected.

[0030] Figure 8 presents a graph in which the amount of natural gas injected is correlated with the dew point temperature of the top gas and with the percentage of hydrogen present in that gas.

[0031] Figure 9 presents a graph showing the environmental benefits, indicated by the amount of CO2 that is no longer emitted into the atmosphere as a function of the amount of natural gas that replaces coke in the operation of a blast furnace. Detailed Description of the Invention

[0032] The present description is merely illustrative, and there is no intention to limit the applications or uses of the present invention, the scope of which is defined in the claims. To facilitate the reading of the description of the embodiments presented herein, the same reference numbers are used to designate the same or equivalent elements in all Figures.

[0033] One aspect of the invention relates to a method of operating a blast furnace in which the combustion of a solid fuel is carried out under specific conditions in order to avoid the formation of soot and ensure complete and efficient combustion.

[0034] Another aspect of the invention relates to a method of operating a blast furnace in which the quantity of a gaseous fuel, for example natural gas, is regulated within predetermined limits, so that the combustion efficiency of the solid and liquid fuels injected into the tuyere is ensured, while maintaining the stable operation of the blast furnace. The operational stability of the blast furnace is monitored by determining the dew point temperature and the H2 content in the top gas.

[0035] Another aspect of the invention relates to the arrangement of three injection lances in a blow tube, such that the injection paths of one lance injecting liquid fuel cross the injection path of the other lance also injecting liquid fuel, promoting turbulence to effectively mix the liquid fuel with the hot air inside the nozzle.

[0036] An additional aspect of the invention relates to the configuration of the lance that injects gaseous fuel, such that the discharge end of this lance can be selectively positioned in relation to the discharge ends of the other two injection lances, allowing the gaseous fuel to ignite according to the oxidation reaction properties of gaseous or liquid hydrocarbon fuels.

[0037] With reference to Figure 1, the numeral 100 generally designates a blast furnace 100 comprising a crucible section 104, where hot metal 106 and slag 108 are collected and periodically discharged. The blast furnace 100 is charged at its top with a mixture of materials 110, mainly composed of iron ore, limestone and coke. The iron oxides in the ore are reduced to metallic iron by reducing gases H2 and CO 112, being melted upon reaching the cohesive zone 114, where heat is generated by the combustion of the coke with oxygen from a stream of hot air 116. This stream of hot air 116 can be enriched with additional oxygen gas 118 to improve the efficiency of coke combustion.

[0038] Hot air 116 is fed to a distributor 120, which distributes it to a plurality of tuyeres 122, by means of respective blast tubes 124. The amount of coke per ton of pig iron, commonly called the coke rate, can be reduced by injecting alternative fuels 126 through the tuyeres 122. The injection of pulverized coal, liquid and gaseous fuels, such as natural gas 128, has become common practice in blast furnace operation, with the aim of reducing the coke rate and, consequently, the environmental impact of CO2 emissions associated with the reduction in coke consumption.

[0039] The reduction of iron oxides by hydrogen generates water vapor, which is released along with other gases such as unreacted CO2, H2 and CO, N2 and CH4, forming the top gas 130 that exits the top of the blast furnace 100. The general operation of blast furnaces is well known and therefore no further details will be included in this description.

[0040] The injection of alternative fuels, however, has significant effects on the operational stability of the blast furnace. Therefore, it is necessary to develop methods and devices that overcome the disadvantages of currently used devices and methods in order to ensure efficient combustion and maintain stable blast furnace operation. The present invention achieves these objectives.

[0041] With reference to Figure 2, the numeral 10 generally designates a blast furnace wall where a tuyere 122 is positioned to provide an opening to the interior 14 of said blast furnace. The tuyere 122 is configured to receive a blowpipe 124 with an open end 18 that fits into the tuyere 122, so that a stream of hot air from the distributor can pass through. 120 is injected into the blast furnace charge 22 through a connecting tube 24. The hot air stream creates a high-temperature coke combustion zone, called the raceway 26, where the coke 22 generates heat and reducing gases H2 and CO.

[0042] The injection of pulverized coal (PCI) through tuyeres 12, by means of a lance inserted into the tuyere 124, has become common practice with the aim of replacing the more expensive coke in the charge with less expensive non-coking coal, without compromising the operation of the blast furnace. Other hydrocarbon fuels, such as liquid petroleum fractions and other light hydrocarbons, for example natural gas, have been used with some advantages.

[0043] In some embodiments, to improve and sustain the combustion of the fuels injected by the tuyeres 122, the hot air is enriched with oxygen 128, which can be introduced by means of an oxygen inlet 30 in the tuyeres 16.

[0044] In a preferred embodiment of the invention, a liquid or gaseous fuel is injected into the hot air stream circulating through the tuyere 122 by means of three injection lances 32, 34 and 36.

[0045] The present invention proposes a 16-valve structure in which three injection lances are inserted at predetermined angles, which can be used for flexible injection of liquid or gaseous fuels 38, 40 and 42.

[0046] With reference to Figures 2 and 3, which schematically show one embodiment of the invention, the longitudinal axis 50 of the lance 32 is positioned in the nozzle forming an angle A with respect to the longitudinal axis X of the nozzle 16, in the range between 5 and 10 degrees, and an angle D in the range between 45 and 55 degrees with respect to the Y-axis, which passes through the midpoint between the longitudinal axes 50 and 52 of the injection lances 32 and 34.

[0047] Boom 34 is positioned in the injection boom 16 so that the longitudinal axis 52 forms an angle B with respect to the longitudinal axis X of the injection boom 16, in the range between 5 and 10 degrees, and an angle E in the range between 35 and 45 degrees with respect to the Y axis, perpendicular to the X axis, passing through the center of said injection boom and between the longitudinal axes 50 and 52 of the injection booms 32 and 34.

[0048] Boom 36 is positioned in the injection boom 16 so that the longitudinal axis 54 forms an angle C with respect to the longitudinal axis X of the injection boom 16, in the range between 5 and 10 degrees, and an angle F in the range between 110 and 130 degrees with respect to the axis Y, which passes through the midpoint between the longitudinal axes 50 and 52 of the injection booms. 32 and 34.

[0049] In some embodiments, the boom 36 can be positioned at different angles relative to the X and Y axes, including parallel to the X axis, since the objective of this boom 36, which carries a gaseous fuel, is to form a high-temperature zone 58 in the vicinity of the region where the liquid fuel is injected.

[0050] In some embodiments, two different types of liquid fuels, for example fuel oil, ethanol, bioethanol, biodiesel and the like, can be injected through injection lances 32 and 34, while a hydrocarbon gas, such as natural gas, propane, butane or the like, can be injected through lance 36. The injection of a hydrocarbon gas improves the combustion of the liquid fuel, since the hydrocarbon gas reacts more rapidly than the droplets of liquid fuel and therefore provides a high-temperature flame zone where the liquid fuel is heated and reacts with the oxygen present in the enriched hot air.

[0051] According to the invention, at least two of the three injection lances 32, 34 and 36 are positioned in the jig 16 so that The jets of liquid fuel injected by lances 32 and 34 have intersecting trajectories, promoting turbulent injection into the tuyere, with better mixing of the liquid particles with the hot air. The other lance, 36, can be positioned so that its gaseous fuel injection trajectory forms a high-temperature flame zone, promoting the combustion of the liquid fuel.

[0052] In some embodiments, alternative fuels are injected into the hot air stream downstream of opening 18 of the tuyere 16 and upstream of opening 17 of the tuyere, since the tuyere 12 is designed to withstand high temperatures and is water-cooled. The injection point of the alternative fuels is chosen to avoid damage to the tuyere 16 and the injection lances used, due to the high temperatures, on the order of 2000 °C, generated by the combustion of these fuels.

[0053] The position of the third nozzle can be adjusted according to the characteristics of the gaseous fuel being injected. If the gaseous fuel is less reactive, its position can be moved forward in the injection direction relative to the liquid fuel injection nozzles, in order to promote the combustion of these liquid fuels.

[0054] In some embodiments, the discharge end of the third injection lance is located at the tuyere at a distance in the range of 200 mm to 400 mm from the discharge end of the first and / or second injection lance.

[0055] Liquid fuel injection can be achieved by adapting the discharge end of the lance, allowing for atomization or micro-pulverization of the material to generate a well-distributed flow, capable of improving combustion kinetics.

[0056] To evaluate the combustion characteristics of fuels on raceway 26, simulations were performed to investigate the effect of different boom configurations. Simulations included a Discrete Element Model (DEM) of a large portion of the blast furnace exposed to the flow from a single tuyere, followed by a Computational Fluid Dynamics (CFD) simulation of compressible, turbulent, and reactive gas flow, including coal combustion. The DEM results were used as input for the CFD simulation, in terms of raceway shape, which was used to define the flow conditions and volumetric resistance in the CFD simulation.

[0057] In this simulation, the gaseous fuel considered was natural gas (approximately 94% methane, 3% propane, and 0.5% butane). The CFD simulation results were subsequently refined through mass and energy balances in order to determine the impact of the combustion efficiency of alternative fuels on the overall blast furnace process.

[0058] To estimate the raceway shape, two operating configurations were considered, with and without natural gas. These configurations correspond to natural gas inlet velocities of 190 m / s and 224 m / s. Simulations were performed using XDEM software, which considers the interaction between a fixed bed of coal particles and the fluid flow. A molar balance equation was calculated to measure the coal combustion efficiency.

[0059] Hot air is operated at a pressure of 4.5 bar (gauge) and an inlet temperature of 1523 K, with variations in mass flow rate and composition. The particle size distribution of the solid fuel varies from 10 µm to 500 µm. The composition is separated into solid, liquid, and gaseous phases. For devolatilization, the double competitive rate model is used. In all cases, the mass flow rate of the solid fuel is kept constant at 2083.33 kg / h, transported by 125 Nm. 3 / ha 60 °C.

[0061] The composition of the combustion products in the raceway was determined, and the results presented in Table 2 were used to estimate the combustion performance, i.e., the combustion efficiency of pulverized coal in each case. Table 2: Mass flow results at the raceway boundary.

[0062] The normalized value of the relative combustion efficiency of coal was calculated for each case, using the maximum coal consumption value as equivalent to 100% relative efficiency, according to the following equation: Relative efficiency of coal = (coal consumed or devolatilized in the case analyzed) / (maximum value of coal consumed or devolatilized among all cases)

[0063] Based on this relative efficiency calculation, the coal burnout was estimated for each case, with 100% being the maximum burnout and 88% the reference burnout for case 2, from which the other values ​​were estimated, according to the equation: Estimated burnout = (relative efficiency of the analyzed case x 88%) / (relative efficiency of case 2)

[0064] The highest relative combustion efficiency of coal was obtained in simulation case 6, which showed approximately 5.3% higher efficiency compared to the efficiency calculated for case 5.

[0065] Figure 5A schematically illustrates case 1, in which a single lance 32 is placed in the tuyere 16 for injecting pulverized coal into the tuyere 122.

[0066] Figure 5B schematically illustrates cases 2 and 3, in which two lances are arranged in the 16th hopper. In case 2, both lances 32 and 36 are used for pulverized coal injection; in case 3, lance 32 is used for pulverized coal injection and lance 36 for natural gas injection.

[0067] Figure 5C schematically illustrates case 4, in which two lances are arranged in the 16th hopper. Lance 32 is used for pulverized coal injection and lance 36 for natural gas injection. Lances 32 and 36, in this case, have a larger diameter than in case 3.

[0068] Figure 5D schematically illustrates case 5, in which three lances are arranged in the tunnel 16. Lances 32 and 34 are used for pulverized coal injection and lance 36 for natural gas injection. The discharge end of lance 36 is... positioned forward in the direction of gas flow relative to the discharge ends of lances 32 and 34.

[0069] Figure 5E schematically illustrates case 6, in which three lances are arranged in the sluice box 16. Lances 34 and 36 are used for pulverized coal injection and lance 32 for natural gas injection. The discharge end of lance 36 is positioned recessed in the direction of gas flow relative to the discharge ends of lances 32 and 34.

[0070] Effective combustion of coal and liquid fuels can be achieved if, among other process factors, good mixing of coal particles or liquid droplets is promoted, as well as sufficient residence time for these fuels to react with the oxygen present in the hot air in the tuyere and raceway. The design of the injection lance arrangement in the tuyere is therefore fundamental to achieving the desired combustion efficiency.

[0071] In some embodiments, the discharge end of the lance carrying a gaseous reducing agent, such as natural gas, can be configured so that its position relative to the discharge ends of the other two injection lances can be adjusted within a range of distances, based on the characteristics of the injected solid or liquid alternative fuel, for example: 1. For natural gas and hydrogen, the third boom can be retracted 60 to 200 mm from the discharge end of the first and / or second boom; 2. For propane gas, coke oven gas (COG) and ethanol, 60 to 400 mm from the discharge end of the first and / or second boom; 3. For butane, 100 to 400 mm from the discharge end of the first and / or second lance.

[0072] As mentioned earlier, injecting alternative solid, liquid, or gaseous fuels through the tuyeres reduces the coke rate, making it desirable to replace as much coke as possible to obtain the benefits of mitigating CO2 emissions and reducing operating costs. However, this substitution affects the blast furnace operation.

[0073] With reference to Figure 6, the amount of natural gas injected per ton of pig iron is correlated with the coke replacement rate (%) and with the solution loss (% of the coke rate). It can be observed that as the injection of natural gas increases, the coke replacement rate increases and the solution loss decreases.

[0074] Solution loss is a type of coke combustion that consumes energy and reduces the energy efficiency of the blast furnace. The solution loss reaction (Ccoke + CO2 = 2CO) is endothermic, therefore its occurrence increases with increasing temperature.

[0075] In some embodiments, the jets of the fuel pump include respective flow control devices to regulate the injection rate of each fuel, so that the solution loss is less than 29%.

[0076] As shown in Figure 6, the theoretical flame temperature resulting from the combustion of alternative fuels—pulverized coal and natural gas—was evaluated as a function of the amount of natural gas injected. Flame temperature is an important parameter to avoid damage from excessive heat generation in the blast furnace and / or tuyeres. It is observed that, with the increase in the amount of natural gas, the flame temperature decreases. Thus, from this point of view, a high injection of natural gas is proposed, above approximately 30 kg / thm³, preferably 49 kg / thm³. Considering an enrichment of the blast air with oxygen to approximately At a concentration of 37%, the flame temperature remained within an acceptable range of approximately 2080 °C. In any case, it would be necessary to increase the oxygen enrichment capacity of the blast furnace infrastructure to support high injection rates of alternative fuels.

[0077] Another important aspect for blast furnace integrity is avoiding excessive moisture condensation in the top gas 130. This risk was assessed by calculating the top gas composition and dew point temperature as a function of the natural gas injection rate.

[0078] Figure 7 shows that a dew point temperature below 100 °C is achieved with an injection of 49 kg / thm³ of natural gas, indicating that this is the maximum permitted injection limit considering this safety parameter.

[0079] With a natural gas injection rate of 49 kg / thm using three injection lances, as per the present invention, the coke rate is reduced by approximately 54 kg / thm and the total fuel rate decreases by about 9 kg / thm. The PCI particle size distribution ranges from 10 µm to 500 µm.

[0080] It appears that injecting 49 kg / thm³ of natural gas with three lances reduces the coking rate by approximately 54 kg / thm³ and promotes a reduction in the total fuel rate of about 9 kg / thm³.

[0081] Figure 9 presents a graph in which the fuel rate and coke rate, measured in kg / thm³, are correlated with the amount of natural gas injected, also measured in kg / thm³. It can be observed that increasing the amount of natural gas injected results in a reduction in fuel and coke rates. The mitigation of CO2 emissions, measured in kt / thm³, increases as the amount of natural gas injected increases. Carbon dioxide mitigation reached values ​​of approximately 283 kt per year in the case of an injection of 49 kg / thm³ of natural gas.

[0082] Some embodiments of the invention have been described herein, but the teachings of the invention can be extended to the injection of other solid, liquid, or gaseous fuels. The injection of these materials leads to the heating of the coal particles, favoring the kinetics of devolatilization and combustion by raising the temperature around the pulverized coal flow.

[0083] It is evident that the embodiments described here are merely illustrative, intended to provide a better understanding of the scope and spirit of the invention, without, however, limiting its reach, which is defined in the appended claims.

Claims

CLAIMS 1. A tuyere for injecting hot air and solid, liquid, or gaseous fuels through a tuyere located in the wall of a blast furnace, characterized by comprising: an elongated body with a discharge end adapted for fluid connection with the tuyere, so that hot air from a hot air distributor is conducted to the interior of the blast furnace, having a longitudinal axis parallel to the direction of hot air injection, and in which the tuyere further comprises three injection lances, wherein a first injection lance and a second injection lance are used for injecting solid and / or liquid fuels, and a third injection lance is used for injecting a gaseous fuel, characterized by: (a) the longitudinal axes and discharge ends of the first and second injection booms being configured to supply the solid and / or liquid fuels at predetermined angles relative to the longitudinal axis of the nozzle; (b) the longitudinal axis and the discharge end of the third boom being configured to deliver the gaseous fuel at a predetermined angle relative to the longitudinal axis of the boom; (c) the discharge ends of the first and second injection lances being located inside the tuyere, closer to the blast furnace charge than to the tuyere; and (d) the position of the discharge end of the third injection lance being located in the tuyere at a distance in the range of 60 mm to 400 mm in relation to the position of the discharge end of the first and / or second injection lance, measured in the direction of the longitudinal axis of the tuyere.

2. Algaraviz according to claim 1, characterized by comprising respective flow control devices for regulating the injection rate of fuels through said injection lances, so that the solution loss is less than 29%.

3. Injection nozzle according to claim 1, characterized in that the longitudinal axis of the first injection nozzle is positioned and oriented in the nozzle forming an angle with respect to the longitudinal axis X of the nozzle in the range between 5 and 10 degrees and forming an angle D in the range between 45 and 55 degrees with respect to the axis Y that passes through the midpoint between the longitudinal axes of the first and second injection nozzles.

4. Injection nozzle according to claim 1, characterized in that the longitudinal axis of the second injection nozzle is positioned and oriented in the nozzle forming an angle B with respect to the longitudinal axis X of the nozzle in the range between 5 and 10 degrees and forming an angle E in the range between 35 and 45 degrees with respect to the axis Y that passes through the midpoint between the longitudinal axes of the first and second injection nozzles.

5. Injection nozzle according to claim 1, characterized in that the longitudinal axis of the third injection nozzle is positioned and oriented in the nozzle forming an angle C with respect to the longitudinal axis X of the nozzle in the range between 5 and 10 degrees and forming an angle F in the range between 110 and 130 degrees with respect to the axis Y that passes through the midpoint between the longitudinal axes of the first and second injection nozzles.

6. Algaraviz according to claim 1, characterized in that the third injection lance is configured and adapted to be movable in the direction of its longitudinal axis, so that the position of the discharge end of said third lance in the tuyere can be selected based on the characteristics of the injected gaseous fuel.

7. Algaraviz according to claim 6, characterized in that the position of the discharge end of the third lance is adjustable based on the characteristics of the injected gaseous fuel, so that its end on the nozzle can be selectively advanced or retracted from 60 mm to 400 mm in relation to the discharge end of the first and / or second injection lance.

8. A nozzle according to claim 7, characterized in that the discharge end of the third lance is positioned recessed in the direction of gas flow by 60 to 200 mm relative to the discharge end of the first and / or second injection lance when natural gas or hydrogen is injected, and by 100 to 400 mm when propane, coke oven gas (COG) or butane is injected.

9. Algaraviz according to any of the preceding claims 1 to 8, characterized in that the liquid fuel is selected from liquefied natural gas, liquefied methane, ethane, propane, butane, ethanol, biodiesel or bioethanol.

10. Method of operating a blast furnace, in which hot air is blown through a tuyere and a tuyere in the wall of said blast furnace, the tuyere comprising three injection lances for injecting solid and / or liquid and / or gaseous fuels, characterized by: injecting solid and / or liquid fuels into the tuyere by means of a first and a second injection lance, whose discharge ends are configured to supply the solid and / or liquid fuels in a first position within the tuyere, closer to the blast furnace charge than to the tuyere; injecting a gaseous fuel by means of a third injection lance in a second position in the tuyere, located at a distance in the range of 200 mm to 400 mm in relation to the first position; and form a high-temperature zone with said gaseous fuel in the vicinity of the region where solid or liquid fuels are injected.

11. Method of operating a blast furnace according to claim 10, characterized by comprising controlling the injection rate of said fuels so that the solution loss is less than 29%.

12. Method of operating a blast furnace according to claim 10, characterized in that the angle formed between the longitudinal axis of the first lance and the longitudinal axis of the blast furnace is between 6 and 7 degrees.

13. Method of operating a blast furnace according to claim 10, characterized in that the angle formed between the longitudinal axis of the second lance and the longitudinal axis of the blast furnace is between 6 and 7 degrees.

14. Method of operating a blast furnace according to claim 10, characterized in that the angle formed between the longitudinal axis of the third lance and the longitudinal axis of the blast furnace is between 8 and 9 degrees.

15. Method of operating a blast furnace according to claim 10, characterized in that the discharge end of said third lance is positioned 60 to 200 mm back from the discharge end of the first and / or second lance.

16. Method of operating a blast furnace according to claim 10, characterized in that the third lance is configured to be movable in the direction of its longitudinal axis.

17. Method of operating a blast furnace according to claim 10, characterized by the position of the end of the The aforementioned third lance is to be selected based on the combustion characteristics of the injected gaseous fuel.

18. Method of operating a blast furnace according to claim 10, characterized in that the discharge end of said third lance is positioned recessed 0 to 200 mm relative to the discharge end of the first and / or second lance when natural gas or hydrogen is injected, and 100 to 400 mm when propane, coke oven gas (COG) or butane is injected.

19. Method of operating a blast furnace according to claim 10, characterized in that the liquid fuel is selected from liquefied natural gas, liquefied methane, ethane, propane, butane, ethanol, biodiesel or bioethanol.

20. Method of operating a blast furnace according to claim 10, characterized in that the gaseous fuel is selected from natural gas, methane, ethane, propane, butane, ethanol, ammonia, synthesis gas from biomass or methanol, and is injected through said third lance.

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