Method for operating a smelting furnace facility

Abstract

A method for operating a smelting furnace installation, in particular a blast furnace installation, comprises the steps of feeding coke, iron oxide-containing material, and optionally fluxing agents to the top of the smelting furnace, injecting a first reducing gas containing hydrogen at a temperature above 1600°C at the tuyere level of the smelting furnace, and injecting a second reducing gas at a lower shaft level of the smelting furnace, wherein the coke is fed at a lump coke rate of less than 220 kg / tHM, preferably less than 200 kg / tHM, more preferably less than 180 kg / tHM, and the density of the first reducing gas is less than 0.80 kg / Nm 3 Less than 0.60 kg / Nm 3 Less than 0.30 kg / Nm 3 is less than.

Description

[Technical Field]

[0001] The present invention relates generally to methods for operating smelting furnace installations, particularly blast furnace installations, and to such smelting furnace or blast furnace installations. [Background technology]

[0002] One of the main concerns for smelting facilities today is CO2 emissions, which are inevitably linked to the very function of the smelter / blast furnace. Conversely, steel production provides the raw material for building CO2-lean technologies, and is therefore a key factor in reducing CO2 emissions.

[0003] Despite the existence of alternative methods and equipment, such as scrap melting and direct reduction processes followed by melting in an electric arc furnace, smelting (i.e., reduction and melting) furnaces such as the blast furnace (BF) remain the most widely used process for steel production today.

[0004] Indeed, blast furnaces have a long tradition in steelmaking, primarily due to their versatility in utilising any type of iron-bearing material. Their drawbacks stem from the fact that they use large amounts of carbon, provided by coke and / or auxiliary fuels, to reduce the ore and to provide the high flame temperatures (over 1800 °C) required to provide the energy needed to reduce, heat and melt the iron and gangue.

[0005] Furthermore, the coke provides a solid matrix within the furnace, allowing sufficient gas permeability in the lower part of the furnace, where the partially reduced iron ore is heated to its melting temperature and then melts in the so-called cohesive zone. In the cohesive zone, the ore material has softened and lost most of its permeability. Therefore, in the cohesive zone, gas primarily passes through the coke layer located in this zone. Below the cohesive zone is the dripping zone, where the molten material drips in a counter / crossflow with the ascending reducing gas flow. For this to occur correctly in both zones, the force exerted by the upstream gas on the downstream droplets must be within certain operating conditions.

[0006] Today, the minimum coke rate in a blast furnace is considered to be about 220 kg / tHM. This limit does not arise for process reasons, but rather from the mechanical and / or hydrodynamic constraints mentioned above.

[0007] In fact, several proposals have been made many years ago to reduce the coke rate even further below 100 kg / tHM, but these very low coke rate process proposals have never been adopted by the steel industry due to the many problems that must be overcome to actually achieve such low coke rates.

[0008] In fact, these problems can occur in various zones of a smelting furnace, especially a blast furnace.

[0009] For example, in an iron-making blast furnace, iron oxide-containing materials descend through the furnace, undergoing processes of reduction, softening, melting, and dripping onto the hearth. At temperatures between the onset of softening and complete melting, they form a cohesive zone. In this cohesive zone, reducing the coke rate reduces the volume of the ascending gas passing through it. This is because the relative thickness of the ore layer increases and the number of coke layers in the cohesive zone decreases. As a result, gas velocity increases, which subsequently accelerates pressure loss in the cohesive zone.

[0010] As the velocity of the rising gas increases in the cohesive zone, the gas tends to spread horizontally toward the wall region and flow upward along the wall region following the path of least resistance. This adverse effect, known as wall channeling, causes heat loss, preferential gas flow through the burden, and consequent non-uniformity in burden relief and temperature, leading to serious operational problems.

[0011] Furthermore, increased bosh gas velocity can prevent the liquid metal and slag from flowing downward through the drip zone, causing flooding.

[0012] In blast furnace shafts, reducing the coke rate to very low values ​​has a significant impact on the porosity of the solid burden. Iron ore particles have small sizes and a wide size distribution, resulting in smaller porosity compared to larger coke particles. The porosity between coke particles is approximately 50%, while for iron ore particles it is only approximately 35% on average. At very low coke rates, the proportion of ore particles becomes very high, which substantially reduces the porosity of the shaft and increases the gas pressure loss within the shaft. This can lead to the so-called hanging phenomenon, where the burden material does not move continuously downward and experiences very high resistance (high gas pressure loss).

[0013] Finally, a minimum coke rate is also required to ensure proper carbonization of the molten iron. In fact, maintaining a stable carbon content is an important prerequisite for ensuring the further conversion of iron to steel. Summary of the Invention [Problem to be solved by the invention]

[0014] An object of the present invention is to provide a method for operating a smelting furnace facility, particularly a blast furnace facility, that can significantly reduce CO2 emissions while adequately addressing the above-mentioned problems. [Means for solving the problem]

[0015] To overcome the above-mentioned problems, the present invention provides in a first aspect a method for operating a smelting (shaft) furnace installation, such as a blast furnace installation, comprising: - feeding coke, iron oxide-bearing and other iron-bearing materials (iron ore, hot briquetted iron (HBI), scrap, etc.), and optionally fluxing agents, into the top of a smelting furnace; - injecting a first reducing gas containing hydrogen at the tuyere level of the smelting furnace at a temperature above 1600°C; - injecting a second reducing gas at the lower shaft level of the smelting furnace; The present invention proposes a method including: According to the present invention, the coke is provided at a lump coke ratio of less than about 220 kg / tHM, e.g., less than about 200 kg / tHM, less than about 180 kg / tHM, less than about 160 kg / tHM, less than about 150 kg / tHM, or less than about 140 kg / tHM, most preferably less than about 130 kg / tHM, wherein the density of the first reducing gas is less than about 0.80 kg / Nm 3 less than, preferably about 0.70 kg / Nm 3 less than, more preferably about 0.60 kg / Nm 3 Less than, for example, about 0.50 kg / Nm 3 Less than 0.45kg / Nm 3 Less than 0.35kg / Nm 3 less than, most preferably about 0.30 kg / Nm 3 is less than.

[0016] In a second aspect, the present invention relates to a smelting furnace installation, in particular a blast furnace installation, comprising: - charging equipment configured to supply coke, iron oxide-containing and other iron-containing materials (iron ore, hot briquetted iron (HBI), scrap, etc.), and optionally fluxing agents, to the top of the smelting furnace; a first injector device arranged at the tuyere level of the smelting furnace and configured to inject a first reducing gas containing hydrogen at the tuyere level of the smelting furnace at a temperature above 1600°C; a second injector device arranged at shaft level of the smelting furnace and configured to inject a second reducing gas at a lower shaft level of the smelting furnace; Equipped with the charging equipment is configured to deliver coke at a lump coke rate of less than about 220 kg / tHM, e.g., less than about 200 kg / tHM, less than about 180 kg / tHM, less than about 160 kg / tHM, less than about 150 kg / tHM, or less than about 140 kg / tHM, most preferably less than about 130 kg / tHM; The first syringe device has a pressure of about 0.80 kg / Nm 3 less than, preferably about 0.70 kg / Nm 3 less than, more preferably about 0.60 kg / Nm 3 Less than, for example, about 0.50 kg / Nm 3Less than 0.45kg / Nm 3 Less than 0.35kg / Nm 3 less than, most preferably about 0.30 kg / Nm 3 configured to inject a first reducing gas having a density less than the first injector device comprises an electric heating device configured to heat the first reducing gas to a temperature greater than 1600°C; A smelting furnace installation is therefore proposed, said smelting furnace installation being preferably adapted and configured to carry out the method according to the first aspect.

[0017] Starting from the premise that substantially reducing the coke rate reduces the permeability of the cohesive zone, the inventors have devised the idea that, in principle, the actual flow rate of the reducing gas (i.e., the first reducing gas, designated A in FIG. 3) passing through the cohesive zone flow path can be significantly reduced, thereby also reducing its velocity, by injecting a second reducing gas into the shaft region (designated B in FIG. 3). Reducing both the velocity and volumetric flow rate of the bosh gas reduces the upward force on the slag and iron droplets, thereby reducing the risk of flooding. However, more importantly, the inventors have realized that an alternative way to reduce the actual mass flow through the cohesive zone would be to use a less dense gas as the first reducing gas. In effect, the density of the first reducing gas can be controlled by reducing the content of dense species, such as carbon dioxide, nitrogen, and water, and / or by increasing the content of less dense species, particularly by increasing the hydrogen content or by introducing helium into the first reducing gas. This inventive method of "avoiding" the permeability problem in the cohesive zone, in turn, can largely prevent the hanging phenomenon in the burden described above and significantly reduce the risk of flooding in the dripping zone. Furthermore, injection of the second reducing gas above the cohesive zone pushes the rising first reducing gas toward the center of the smelting furnace (as shown in Figure 3), thereby mitigating the wall channeling problem described above. Furthermore, injection of the first reducing gas at temperatures above 1600°C can provide a significant portion of the thermal energy required to heat and melt the burden.

[0018] The introduction of less dense species such as hydrogen, helium, or mixtures thereof can reduce the actual mass flow of the (first) reducing gas, while still providing the required thermal energy. Indeed, as shown in the table below, the specific heat capacity of helium, and especially hydrogen (here, approximately at the target temperature: about 1527°C), is significantly higher than that of other gases, such as CO or N2, which means that a much higher amount of heat is released per mass unit of hydrogen or helium to reduce the temperature by one unit.

[0019] Table: Specific heat capacity of various gases TIFF2025529131000002.tif19170

[0020] However, helium and hydrogen are particularly preferred, as the latter, beyond its role as an efficient heat vector, also possesses a reduction potential that is directly useful in the blast furnace.

[0021] Nevertheless, simultaneous injection of a second reducing gas at the lower shaft level (and appropriate control thereof) can therefore at least maintain and preferably increase the production of liquid iron compared to more conventionally operated blast furnaces. Alternatively or additionally, injection of a second reducing gas at the lower shaft level (and appropriate control thereof) can reduce the lump coke rate to values ​​below 160 kg / t of liquid iron.

[0022] In an embodiment, the second reducing gas may have a slightly higher density than the first reducing gas, but the density of the second reducing gas is 1.2 kg / Nm 3 Less than 1.0 kg / Nm 3 Less than 0.9kg / Nm 3 It is desirable that it be less than this.

[0023] In embodiments, the first reducing gas may be injected at a pressure between 2 bar absolute and 10 bar absolute, preferably between 4 bar absolute and 5 bar absolute, or even between 5 bar absolute and 6 bar absolute. According to the same or other embodiments, the second reducing gas may be injected at a pressure between 2 and 10 bar absolute, preferably between 4 and 5 bar absolute.

[0024] Although the process of the present invention does not preclude burning coke to generate both heat and reducing species, it is generally preferred to use injected oxygen at a concentration of, for example, about 300 Nm 3 / tHM or approximately 250Nm 3 / tHM or about 200Nm 3It is advantageous to reduce the amount of HCl from above 1 / tHM to a low to very low flow rate. Thus, in a particularly preferred embodiment, the method comprises the following steps: -For example, about 120Nm 3 / tHM less, about 180Nm 3 / tHM less, approx. 160Nm 3 / tHM or less, or approximately 140Nm 3 / tHM, preferably less than about 112 Nm 3 / tHM, more preferably, an amount less than about 80 Nm 3 / tHM less than approx. 40Nm 3 / tHM or approximately 20Nm 3 / tHM less, about 100Nm 3 injecting oxygen at the tuyere level of the smelting furnace in an amount less than / tHM.

[0025] Advantageously, the temperature of the injected oxygen is below 600° C., preferably below about 400° C., such as below about 300° C., below about 200° C., or even about ambient temperature. The oxygen is preferably injected in a concentrated form, such as commercially pure oxygen, having an oxygen content of at least about 75% by volume, more preferably at least about 90% by volume or at least about 95% by volume. Although, as mentioned above, it is desirable to reduce the amount of oxygen injection at the tuyere level, in order to limit not only the actual amount of gas passing through the cohesive zone channels but also to minimize coke combustion, the inventors have discovered that raceways, i.e., void spaces typically found in front of the tuyere of blast furnaces operated with hot blast oxygen, which serve to properly distribute gas within the blast furnace bosh, can be mechanically achieved by high injected gas velocities, for example, greater than 150 m / s, more preferably greater than 170 m / s, and even more preferably greater than 200 m / s, when oxygen is not injected at tuyere level (and therefore coke is not burned in front of the tuyere). It is noted in the present invention that the formation of raceways is also at least partly due to the direct gasification of the coke by the effect of the injected very hot first reducing gas, as will be explained in more detail below. However, both this mechanical action and the contribution of the injected first reducing gas to the direct gasification of the coke may not be sufficient to adequately "blow" the void space in front of the tuyere, making it desirable or necessary to inject a relatively small amount of oxygen compared to the flow rate typically used in conventional hot-blast blast furnaces. Therefore, in the present method, it may be advantageous to inject a "track-forming," "track-maintaining," or "track-supporting" amount of oxygen, i.e., an amount of oxygen sufficient to form or maintain the size and shape of the track behind the injection point of the first reducing gas by burning an appropriate amount of coke in this region, or an amount of oxygen sufficient to support or complement the mechanical and gasification effects described above. Oxygen injection may be continuous or intermittent, and may even be individually controlled according to the actual needs regarding the size and shape of the track. In an embodiment, the flame temperature may be adjusted to a temperature of 1700°C to 2600°C, preferably 1800°C to 2400°C, and more preferably 1800°C to 2300°C.

[0026] In the present context, it will be apparent that a "blast furnace" operated in accordance with the present invention is not actually a "blast" furnace as such, since the present invention essentially replaces the blast with a first reducing gas as defined herein. However, for convenience, as used herein, the expression "blast furnace" can refer to a furnace operated with an air / oxygen-containing blast in the context of a conventional (operated) shaft reduction melting (smelting) furnace, or to a shaft reduction melting furnace operated as described herein, in which case the blast is essentially replaced with a reducing gas, referred to herein as the first reducing gas.

[0027] Generally, the first reducing gas is injected at the tuyere level at a rate of less than about 800 kg / tHM, preferably less than about 775 kg / tHM, less than about 750 kg / tHM, less than about 700 kg / tHM, less than about 650 kg / tHM, and most preferably less than about 600 kg / tHM. When the lump coke rate is low, the mass flow rate of injection at the tuyere is generally lower. However, since a minimum flow rate of the first reducing gas must be ensured, the first reducing gas may be injected at a mass flow rate of preferably more than 60 kg / tHM, preferably more than 120 kg / tHM, more than 180 kg / tHM, or even more than 300 kg / tHM. In an embodiment, the first reducing gas is injected at a rate of 500 to 1300 Nm 3 / tHM, preferably between 900 and 1300 Nm 3 Between / tHM, preferably between 770 and 1000Nm 3 / tHM.

[0028] The first reducing gas may be injected at a mass flow rate of more than 20 kg / tHM, preferably more than 50 kg / tHM, whereas the second reducing gas is preferably injected at a flow rate of less than 600 kg / tHM, preferably less than 400 kg / tHM, or even less than 360 kg / tHM. Additionally or alternatively, the second reducing gas may be injected at a flow rate of between 200 and 800 Nm 3 / tHM, preferably between 250 and 700 Nm 3 Between / tHM, preferably between 250 and 600 Nm 3 It may be injected at a volumetric flow rate between 0.15 and 0.25 M / tHM.

[0029] The first and / or second reducing gases usable in the present method typically comprise synthesis gas. While this synthesis gas can be obtained from any suitable process or source, the present method preferably includes a further step of producing such synthesis gas by reforming, in particular by reforming coke oven gas, natural gas, and / or other (lower) hydrocarbons or mixtures thereof, in particular with CO and / or HO. Preferably, the supply of these components may originate from the reforming of smelting furnace (autogenous or non-autogenous) top gas, basic oxygen furnace (BOF) gas, open bath furnace (OBF), or other off-gases or process gases from steel plants. It may also be suitable to use high-temperature oxygen to reform hydrocarbons resulting from the combustion of steelworks by-products, such as tar and coke breeze, into pure oxygen. Other suitable processes include subjecting smelter furnace top gas, coke oven gas, BOF gas, and / or OBF gas to monoethanolamine (MEA) absorption, membrane separation, pressure swing adsorption (PSA), or vacuum pressure swing adsorption (VPSA). Depending on the starting material, reforming can be carried out by any suitable catalytic or non-catalytic reforming process, or by a combination of more such processes, such as steam reforming or dry reforming. Advantageously, smelter furnace top gas can be used as a CO and / or HO source in hydrocarbon reforming and thus reused in the preparation of the first and / or second reducing gases. Additionally or alternatively, reducing gases can also be produced from hydrocarbon sources using autoreforming or partial oxidation techniques.

[0030] According to a preferred embodiment of the present invention, the first reducing gas contains hydrogen. Indeed, the inventors have discovered that denser species can be eliminated and / or less dense species can be added to alleviate the problems of space reduction when reducing the coke rate, particularly permeability problems in the cohesive zone, while simultaneously reducing the effects of flooding in the lower dripping zone and hanging in the upper burden. As mentioned above, the use of, for example, hydrogen, helium, or both, to influence the density of the first reducing gas is expressly contemplated herein. Using a reducing gas with a certain proportion of hydrogen is highly desirable because this gas has a much lower density and much lower (dynamic) viscosity than any other gas, yet is still useful as a reducing agent. Indeed, the inventors have discovered that reducing the density of the first reducing gas results in a desirable lower pressure drop along the entire smelting / blast furnace, particularly through the cohesive and dripping zones. Increasing the proportion of hydrogen further reduces the (dynamic) viscosity of the reducing gas, which also leads to better flow and distribution of the first reducing gas, especially through both the cohesive and dripping zones. Therefore, the first reducing gas can advantageously be a hydrogen-rich gas, such as hydrogen-rich synthesis gas or gas resulting from ammonia decomposition and / or methanol decomposition and / or ethanol decomposition. The first reducing gas can have a hydrogen content of more than about 30% by volume, preferably more than about 35%, more than about 40%, or more than about 50% by volume. Values ​​of more than about 60%, more than about 65%, more than about 70%, more than about 75%, more than about 80%, more than about 85%, more than about 90%, more than about 95%, or even more than about 98% by volume are also possible.

[0031] Thus, the first reducing gas can be any suitable reducing gas having the above-mentioned density. In particular, the first reducing gas can comprise or consist of synthesis gas, such as that obtained from known reforming processes. It is particularly preferred that the molar ratio (H2 + CO) / (H2O + CO2) is greater than about 7, preferably greater than about 8, and more preferably greater than about 9. This molar ratio can also be even higher, such as greater than about 12 or greater than about 15. Alternatively or additionally, the first reducing gas can comprise or consist of gas resulting from the decomposition of ammonia (N2 + 3H2) and / or the decomposition of methanol and / or the decomposition of ethanol. In either case, these reducing gases can be enriched with hydrogen as described above, if necessary or desired.

[0032] It is particularly preferred that the first reducing gas provides the energy required for heating, melting, and proper progression of iron oxide reduction, or at least a significant portion of it. The required heating naturally depends on the initial temperature of the first reducing gas before it is heated to the actual required temperature. Depending on prior processes such as the type of reforming, the first reducing gas generally has an initial temperature of 800°C to 1500°C, for example 900°C to 1300°C. Since it is preferred to inject the first reducing gas at a temperature of about 1600°C to about 2600°C, more preferably at a temperature above about 1800°C or about 1900°C, and most preferably above about 2000°C, for example above about 2150°C, above about 2300°C, above about 2425°C, or even above about 2500°C, the remaining heating being provided by one or more suitable heaters, as further described below. In particularly advantageous embodiments of the method, the actual temperature of the first reducing gas is controlled based on a number of operational parameters of the smelting furnace installation, such as, for example, the temperature, pressure, mass / volume flow rate and composition of the furnace gas, specific charging parameters of the smelting furnace, such as the temperature and flow rate of coke, iron oxide-containing material and / or fluxing agents, measurements indicative of the current operating conditions at various locations within the smelting furnace, such as temperature, pressure, product composition and temperature, and of course the production rate, etc. In particular, the temperature of the first reducing gas can also be controlled as a function of the temperature of the second reducing gas (among other things), or vice versa, as will be further explained below.

[0033] In an embodiment, the smelting furnace installation may further comprise at least one sensor adapted to analyze the composition of the gas at the top of the smelting furnace for CO, CO2 and / or H2 concentrations in the gas, and optionally also adapted to analyze the composition of the gas for HO, N2 and / or CH4 concentrations in the gas. The sensor may be at the top level in the furnace or may be connected to piping that removes the gas from the top level of the furnace.

[0034] The sensor can be any type of sensor adapted to determine gas composition, such as, for example, electrochemical, catalytic bead (pellistar), photoionization, infrared spot, infrared imaging, semiconductor, or ultrasonic. The semiconductor type sensor can be a metal oxide semiconductor sensor. The sensor can be included in a gas chromatograph.

[0035] Any known process or combination of known processes may be used to provide the first reducing gas with the required energy, and thus the desired temperature, possibly depending on the initial temperature of that reducing gas. The first reducing gas is preferably heated by one or more electric heaters before injection into the smelting furnace. Because the anticipated temperatures are quite high, particularly when temperatures exceeding about 1800°C are reached, it may be useful or desirable to provide additional heat as late as possible before the actual injection takes place, for example, by providing at least a portion of the heating downstream of the bustle pipe, for example, by one or more plasma torches located in the blast pipe, such as after the downleg, preferably in the blowpipe, or even in the tuyere itself, most preferably in any suitable position in the blowpipe or in the tuyere. Nevertheless, it is also possible, and expressly contemplated herein, for example, to locate (additional) heaters, such as resistance heaters or plasma electric heaters, upstream of the blast pipe, for example, in the bustle pipe, or even upstream of the bustle pipe (downstream of the reforming). In preferred embodiments, the first reducing gas may be heated by electric heaters (i.e., electrically driven heaters), each of which is adapted to operate at a power of 200 to 700 kWh / tHM, 250 to 600 kWh / tHM, or 300 to 550 kWh / tHM.

[0036] When the first reducing gas is heated (at least partially) by one or more plasma torches located, for example, in the blowpipe of the blower, the plasma torches are preferably electrode-based or electrodeless plasma torches, such as those selected from induction-ignition plasma torches, microwave plasma torches, radio-frequency plasma torches, and combinations thereof. Suitable plasma torches are DC or AC plasma torches, such as three-phase AC plasma torches, and the plasma torches generally have a power rating of 1 MW to 10 MW, preferably 2 MW to 6 MW, and most preferably 4 MW to 5 MW. Further details regarding suitable plasma torches and their appropriate locations within the smelting furnace installation are provided below.

[0037] In contrast to the first reducing gas, the second reducing gas is generally not injected at a significantly higher temperature, although similar temperatures may be used if deemed desirable or necessary. Indeed, in most cases, the second reducing gas is preferably injected at a temperature of about 800°C to about 1200°C, more preferably about 900°C to about 1100°C, and most preferably below about 1000°C, e.g., below about 950°C. As already mentioned in the context of the temperature of the first reducing gas, the actual temperature of the second reducing gas is preferably controlled based on a number of operational parameters of the smelting furnace system, such as, for example, the coke reactivity temperature, pressure, mass / volume flow rate, and composition of the furnace gas; specific charging parameters of the smelting furnace, such as the temperature and flow rate of coke, iron-oxide-containing material, and / or fluxing agents; and measurements indicative of current operating conditions at various locations within the smelting furnace, such as temperature, pressure, gas composition, etc. In particular, the temperature of the second reducing gas may be controlled as a function of the temperature of the first reducing gas (among other things), or vice versa.

[0038] The smelting furnace facility may further include a gas injection adjustment device configured to adapt the composition of the gas and / or the volume of the gas injected by the first and / or second injector devices based on the determined gas composition and / or furnace top temperature.

[0039] The gas injector regulator may also adapt the power supply to the at least one electric heater based on the determined gas composition at the furnace top level and / or the temperature at the furnace top level.

[0040] The gas injector adjusting device may also be configured to adapt the composition of the gas and / or the volume of the gas injected and / or the temperature of the gas injected by the first and / or second injector devices based on the composition and / or temperature of the molten iron output by the smelting furnace and the production rate of the molten iron.To determine the composition of the molten iron output by the smelting furnace and the production rate of the molten iron, the smelting furnace installation may include further sensors arranged at the molten iron outlet of the furnace configured to determine the composition of the molten iron and to determine the volume of the molten iron.

[0041] In the present invention, a lower proportion of lump coke is fed to the smelting furnace compared to conventionally operated blast furnaces. However, particularly in the cohesive zone, permeability to gases is significantly reduced due in part to the fact that molten slag penetrates the coke layer, thereby occluding part of its height. Because this reduces the permeability height of the coke layer, it is generally desirable not to feed coke to layers that are not at a minimum height. Such a minimum height is generally at least about 8 cm, e.g., at least about 10 cm, e.g., 9-11 cm, at least about 12 cm, or at least about 15 cm, e.g., 14-15 cm.

[0042] In a further embodiment, the method disclosed herein further comprises adjusting the average degree of reduction of the iron oxide-containing material reaching the cohesive zone to a value greater than about 80%, more preferably greater than about 85%, in particular by controlling the amount (injection rate) and / or composition of the second reducing gas injected at shaft level as a function of the amount (injection rate) and / or composition of the first reducing gas injected at tuyere level and / or the amount (injection rate), if any, of oxygen injected at tuyere level.

[0043] As previously mentioned, the required lump coke ratio depends, among other things, on the amount of coke consumed in the direct reduction of iron ore. Thus, in embodiments, the lump coke ratio can be reduced by controlling lump coke consumption for direct reduction, which can in turn be controlled by adjusting the amount (injection rate) and / or composition of the second reducing gas injected at the shaft level as a function of the amount (injection rate) and / or composition of the first reducing gas injected at the tuyere level and / or the amount (if any) of oxygen injected at the tuyere level. Thus, by controlling coke consumption for direct reduction to less than about 60 kg / tHM, preferably less than about 50 kg / tHM, and more preferably less than about 40 kg / tHM, the lump coke ratio can be (further) reduced to a value less than 220 kg / tHM.

[0044] Alternatively or additionally, the method preferably further comprises a step of reducing / limiting the channeling effect / phenomenon above the cohesive zone by controlling the injection (flow rate, velocity, and pressure) of the second reducing gas at (the lower part of) the shaft of the smelting furnace. This advantageous effect is achieved by injecting the second reducing gas at shaft level, preferably along the periphery of the smelting furnace, so that the gas rising from the cohesive zone is centered within the smelting furnace. Therefore, it is desirable that the first reducing gas injectors (i.e., tuyere) and / or the second reducing gas injectors are uniformly distributed from each other, generally at intervals of between 0.5 and 2.5 m, preferably between 1.0 and 1.5 m. Furthermore, it is advantageous that the injection velocity of the second reducing gas at shaft level can be controlled to a value between 40 and 250 m / s, preferably between 80 and 200 m / s. It is also generally useful or desirable to control the ratio of the volumetric flow rate of the second reducing gas (injected at shaft level) to the volumetric flow rate of the first reducing gas (injected at tuyere level) to a value of from 0.1:1 to 1:1, preferably from 0.2:1 to 0.8:1, more preferably from 0.33:1 to 0.7:1, or even from 0.4:1 to 0.7:1, 0.65:1, or 0.6:1.

[0045] As already mentioned above, the second reducing gas usable in the present method typically comprises synthesis gas. It may also consist solely of synthesis gas, meaning that the second reducing gas has the composition obtained, for example, from a reforming process, preferably the reforming process described above. Regardless of the source or pre-treatment of the second reducing gas, it is particularly preferred to have a molar ratio (H + CO) / (H O + CO) of greater than about 6, preferably greater than about 7, and more preferably greater than about 8. This molar ratio can also be higher, such as greater than about 12 or greater than about 15. In embodiments, this molar ratio may be less than about 80, or less than about 30.

[0046] The second reducing gas may be enriched with hydrogen, such as hydrogen-enriched syngas, which, regardless of its original composition, advantageously has a (final) hydrogen content of greater than about 30% by volume, preferably greater than about 40% by volume, and more preferably greater than about 50% by volume.

[0047] It is further preferred that the first reducing gas and / or the second reducing gas, preferably both, are essentially free of nitrogen, if any, and thus the first reducing gas and the second reducing gas (independently) have a nitrogen content of less than about 35% by volume, more preferably less than about 15% by volume, even more preferably less than about 10% by volume, and most preferably less than about 5% by volume.

[0048] The method of the present invention also includes active control of the pressure level of any gas injected at the tuyere. The pressure level of the smelting furnace at the tuyere level is advantageously controlled to a value above about 2 barg, preferably above about 4 barg, and more preferably above about 5 barg. In fact, a higher pressure level also has a positive effect on the flooding phenomenon, i.e., the pressure on the droplets. A higher pressure increases the density, but also reduces the gas velocity. Since the effect of gas on the droplets depends more strongly on velocity (power of 2) than on density, an increase in pressure helps to further improve the situation in the cohesive and dripping zones.

[0049] In an advantageous embodiment, the method further comprises the step of reducing channeling and flooding effects by controlling the top pressure of the smelting furnace in the range of 1 to 10 bar, more preferably in the range of 2 to 7 bar, and most preferably in the range of 3 to 5 bar.

[0050] Alternatively or additionally, the method may further comprise the step of reducing the inner wall channeling effect of gas coming from the cohesive zone to the furnace wall in the lower shaft zone by controlling the injection conditions of the second reducing gas, for example, specifically the injection rate and / or ratio of the second reducing gas injected into the shaft of the smelting furnace.

[0051] The method may advantageously include the further step of reducing the carbon dioxide content of any one or more carbon dioxide-containing off-gases and / or process gases produced during operation by carbon capture and utilization (CCU) and / or carbon capture and storage (CCS).

[0052] In this context, it is of particular interest to use at least a portion of the captured CO2 in so-called synthesis gas production plants, for example by converting the carbon dioxide together with CO2-diluted hydrogen into synthesis gas and further by methanation into synthetic hydrocarbons such as natural gas, and / or by any other suitable production process, including biological processes, to produce methane, methanol, ethanol, etc. All or part of the methane, methanol, ethanol, etc. can then be used to produce synthesis gas and injected into a blast furnace.

[0053] As already mentioned above, it may also be advantageous to incorporate ammonia (NH3) and / or cracked ammonia (N2 + 3H2) as a hydrogen-rich fuel within the range of the tolerable nitrogen concentration of the synthesis gas for use as (or in) the first and / or second reducing gas in the present method. Indeed, this is of particular interest if ammonia becomes commercially available as a CO2-free energy carrier with a high hydrogen content.

[0054] The expressions "shaft level" or "injecting... at the shaft level of the smelting furnace" mean that the injection takes place in the lower shaft zone above the hot blast / tuyere level, in particular above the bosch, preferably in the ferrous oxide gas-solid reduction zone above the cohesive zone. Therefore, injection at the shaft level is preferably carried out (e.g., immediately) above the root of the cohesive zone, in the region of the cohesive zone that is in direct contact with the furnace wall (i.e., above the root of the cohesive zone). In other words, the equivalent expressions "shaft level" or "lower shaft level" refer to a level at which the injected gas can participate in the reduction reaction, preferably at the level of the FeO reduction zone. Conversely, the expressions "tuyere level" or "injecting... at the tuyere level of the smelting furnace" mean that the injection takes place at a level where tuyere openings for hot blast are conventionally provided, preferably below the bosch, i.e., using conventional tuyere openings well below the cohesive zone.

[0055] An "injector apparatus" in this context should be understood as comprising one or more injectors, and optionally including any corresponding associated upstream connecting conduits, piping and regulation and control components, reduction gas treatment / heating / cooling, etc. Depending on the particular context, a first injector apparatus located at tuyere level may therefore refer to one or more tuyere(s) themselves, or to a tuyere(s) with any one or more associated upstream components, such as a blowpipe assembly or blast pipe, a bustle pipe, a first reduction gas treatment or heating unit, connecting piping and control components, etc. Similarly, depending on the particular context, a second injector apparatus located at shaft level may refer to one or more shaft injectors themselves, or to a shaft injector(s) with any one or more associated upstream components, such as an injector feed assembly, a shaft ring pipe, a second reduction gas treatment or heating unit, connecting piping and control components, etc.

[0056] In embodiments, the first injector apparatus may comprise at least 10 first gas injectors (i.e., tuyere) and up to 70 first gas injectors (i.e., tuyere), preferably 18 to 40 first gas injectors. According to the same or other embodiments, the second injector apparatus may comprise at least 10 second gas injectors and up to 70 second gas injectors, preferably 18 to 40 second gas injectors.

[0057] The expression "equivalent coke rate" includes all (ambient temperature) carbonaceous gaseous, solid, or liquid materials fed to the smelting furnace, including the actual coke material (fed at the lump coke rate), but also includes additional carbonaceous gaseous, solid, or liquid materials that may be added to the smelting furnace during operation, such as gaseous methane, natural gas, and / or pulverized coal injected at the tuyere level. Pulverized coal or additional carbonaceous gaseous, solid, or liquid materials may be injected at the tuyere level if it is considered desirable or useful to provide the required energy by being burned in the furnace, for example, when the first reducing gas is injected at a temperature below 1600°C (temporarily, for example, due to lack of heating means) and / or upon restart after a maintenance outage. However, the injection rate of additional carbonaceous materials is preferably less than 150 kg / tHM, more preferably less than 120 kg / tHM. However, the present method does not provide for the feeding of such additional gaseous, solid, or liquid carbonaceous material to the smelting / blast furnace; in particular, the present method does not contemplate or include the injection of pulverized coal into the smelting / blast furnace, but most preferably only contemplates or includes the feeding of coke as the carbonaceous solid material to the top of the smelting / blast furnace. Therefore, the expression "lump coke ratio" as used herein refers to the proportion of coke material actually added to the top of the blast furnace. Indeed, "lump coke" refers to the coke charged to the furnace, generally of a size greater than 20 mm. In a preferred embodiment, the furnace is operated at an equivalent (gross) coke ratio of less than 220 kg / tHM, preferably less than 200 kg / tHM, and more preferably less than 180 kg / tHM.

[0058] The ratio expressed as " / tHM" indicates per ton (metric ton) of liquid iron produced in a blast furnace facility. 3 " refers to the normal cubic meter and indicates the volume of one cubic meter of gas under normal conditions, i.e., a temperature of 0°C (273.15 K) and an absolute pressure of 1 atmosphere (101.325 kPa).

[0059] In this context, the term "hydrogen-enriched" or "enriched with hydrogen" in reference to a gas (mixture) means that hydrogen gas (H) has been actively and intentionally added to the gas (mixture) to increase the molar fraction of hydrogen in the resulting hydrogen-enriched gas (mixture).

[0060] In this context, the oxygen injection rate at the tuyere level refers to the total amount of oxygen injected.

[0061] By "reducing gas" in the present context is meant a gas that is involved in, i.e. is capable of carrying out, a reduction reaction, i.e. a gas that contains reducing species such as H2 and / or CO, preferably with H2 representing 30-100% by volume, CO representing 10-70% by volume, and compounds other than CO and H2 representing less than 35% by volume of the reducing gas, more preferably less than 10% by volume or even less than 5% by volume. In an embodiment, the reducing gas has a hydrocarbon concentration of less than 25% by volume, preferably less than 20% by volume, more preferably less than 10% by volume.

[0062] "About" in this context means that a given numerical value covers a range of values ​​from -10% to +10% of the numerical value, preferably from -5% to +5% of the numerical value, or even from -2.5% to +2.5% of the numerical value.

[0063] The method of the present invention and the additional variations disclosed herein have many important advantages and benefits. -low CO2 emissions, - no or limited changes to the layout and logistics of the steel plant, and the method can be implemented in existing blast furnaces with only limited modifications; - Shaft injection can reduce the tuyere gas volume by approximately 15 to 30%, thereby reducing the thickness of the lump coke layer by approximately 25 to 50%. - H2 in the first reducing gas allows to reduce the dynamic viscosity of this gas by about 15%, resulting in higher speeds with the same pressure drop and the same force on the coke particles and droplets; - H2 in the first reducing gas allows to reduce the density of this gas by about 50%, resulting in higher velocities with the same pressure drop and the same force on the coke particles and droplets. -No or little coke combustion in the smelting furnaces, so no or little oxygen is required; - Pulverized coal or auxiliary fuel injection is usually not required to achieve very low coke consumption; -Restartup is easy because synthesis gas is generated outside the reactor through steam reforming or H2 injection during ramp-up. [Brief explanation of the drawings]

[0064] Preferred embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Figure 1] 1 is a schematic diagram of an advantageous embodiment of the present invention; [Figure 2] 1 is a schematic, partially cut-away view of an advantageous embodiment of (part of) a first injector device useful in the present invention; [Figure 3] The zones in the blast furnace and the effect of lower shaft injection of reducing gas B on the rising gas passing through the coke layer in the cohesive zone are shown.

[0065] Further details and advantages of the present invention will become apparent from the detailed description that follows. DETAILED DESCRIPTION OF THE INVENTION

[0066] General Considerations

[0067] The main problem with blast furnaces in terms of CO2 emissions is that the process is based on coke-based reduction of iron ore and the injection of a carbon-rich auxiliary fuel / reducing agent at tuyere level.

[0068] Injection of syngas at the shaft or even tuyere level has been proposed to help reduce coke consumption in blast furnaces and therefore CO2 emissions. However, even under these conditions, a non-negligible lump coke rate is required, typically still exceeding 300 kg / tHM. This still substantial coke rate requirement is primarily due to process, with minor mechanical / hydrodynamic reasons.

[0069] Today, the blast furnace appears increasingly to be overtaken by alternative process routes that require only small amounts of coke. These processes effectively split the blast furnace into two sections: iron ore reduction, performed in a shaft furnace, and melting, performed in an electric smelting furnace, which uses a type of electric arc / plasma or submerged electrode. However, this concept results in very large, complex installations that are both costly to capitalize and difficult to maintain. Furthermore, when utilizing hydrogen-reduced direct reduced iron (DRI), the smelting furnace still requires a significant amount of coke—approximately 60 to 110 kg / tHM. This carbon is needed to complete the reduction of the DRI and to carbonize the molten iron, which is then processed in a basic oxygen furnace.

[0070] The present method aims to show that widely used blast furnace technology, if suitably converted as described herein, can provide a solution for CO2 emission reduction, whereby improving the blast furnace process conditions allows the use of (modified) blast furnaces with very low coke rates.

[0071] In fact, today's conventional blast furnaces use coke to meet various requirements. -Indirect reduction of iron ore in shafts: 3Fe2O3+CO → 2Fe3O4+CO2 and Fe3O4+CO → 3FeO+CO2 - Direct reduction of molten iron oxide in the lower part of the blast furnace: FeO + C → Fe + CO -Solution loss: At certain temperature levels, coke reacts with carbon dioxide and H2O to produce carbon monoxide and H2: C+CO2←→2CO C+H2O←→CO+H2 -Carbonization of molten iron. At a typical operating temperature of a blast furnace, around 1500°C, carbon-saturated iron has about 4-5% dissolved carbon. This temperature level is also a prerequisite for blast furnaces, as molten iron can become liquid at this temperature level. -The burning of coke in the tuyere to generate the hot reducing gas needed to melt and reduce the iron ore. The hot reducing gas must reach the minimum flame temperature (1800 to 2600°C) required for blast furnace operation. In effect, the flame temperature ensures heat transfer from the gas phase to the ore and its subsequent melting. If this temperature is too low, the blast furnace cannot achieve high productivity. -Due to chemical equilibrium, about half of the reducing gas produced in the blast furnace is discharged from the top (top gas) without reacting. Of the remaining calorific value of the top gas, typically one-third is used to heat the hot blast, and two-thirds is exported from the blast furnace plant.

[0072] For today's standard blast furnace application, with a coke rate of 310 kg / tHM and pulverized coal injection (PCI) of 180 kg / tHM, the coke consumption among the various factors is distributed as follows (see Table 1):

[0073] [Table 1]

[0074] The problem is how to reduce this coke ratio.

[0075] Coke dissolved in molten iron cannot actually be reduced because it dissolves in the molten iron until it is saturated. Saturation of the molten iron with carbon extends the life of the carbon blocks in the hearth. Therefore, it is theoretically impossible to reduce this 47 kg / tHM (see Table 1).

[0076] Increasing the reduction degree of the ore coming from the upper part of the blast furnace allows for a significant reduction in the coke required for direct reduction in the lower part of the blast furnace. The reduction degree can be increased by increasing the ratio of reducing agent to oxidizing agent in the gas phase in the blast furnace shaft (CO + H2) / (CO2 + H2O). This can be done by increasing the reducing gas flow, for example by injecting reducing gas at the bottom of the shaft. Another option is to increase the accumulated concentration of H2 + CO by reducing the N2 content in the injected gas, mainly at the tuyere and shaft levels.

[0077] Coke required for solution loss can also be reduced by increasing the ratio of reducing agent to oxidizing agent in the gas passing through the shaft of the blast furnace. This can be done by increasing the reducing gas flow, for example by injecting reducing gas at the bottom of the shaft. Again, this can be done by increasing the accumulated concentration of H2 + CO, for example by reducing the N2 content in the injected gas at the tuyere level and shaft level.

[0078] The energy required for the lower part of the blast furnace is generated at the tuyere level, where coke and auxiliary fuels such as PCI or natural gas are burned and gasified in hot air (between 900 and 1300 °C), producing tuyere gases at temperatures between 1800 and 2500 °C. The fuel is oxidized to CO only, not CO2, which requires the combustion of large amounts of fuel. As a result, very little heat of reaction is released, resulting in a much lower flame temperature than would be achieved by completely burning the fuel to CO2 and H2O in an oxidizing atmosphere.

[0079] What this invention proposes:

[0080] The present invention proposes to combine both types of injection, utilizing reducing gas in the blast furnace injected at both the bottom of the shaft and at tuyere level, with the reducing gas injected at tuyere level being further heated to a temperature equivalent to or as close as possible to the normal blast furnace flame temperature. Thus, the present invention contemplates heating the tuyere reducing gas, e.g., synthesis gas, to at least 1600°C, preferably above 1800°C, more preferably above 2000°C, and in some cases above 2300°C.

[0081] When injecting hot reducing gas at the shaft and tuyere level, the method completely avoids the need for hot blasts containing oxygen a priori. However, for example, 120 Nm 3 / tHM less than 112Nm 3 It is still possible to maintain small amounts of injected low temperature oxygen, less than 1 / tHM, at the tuyere if desired or deemed useful, with or without some auxiliary fuel such as natural gas, coke oven gas, pulverized coal, etc. Typically, the minimum injection rate of oxygen at the tuyere level is about 4 Nm 3 / tHM above, for example, about 12 Nm 3 / tHM over, about 25Nm 3 / tHM above, for example, about 35Nm 3 / tHM or even about 50Nm 3 / tHM is beyond.

[0082] To heat the (first) reducing gas, various methods can be used to efficiently heat the reducing gas, for example from the synthesis gas production temperature (approximately 950°C for catalytic reforming processes and partial oxidation / autothermal reforming, approximately 1200°C for non-catalytic reforming processes, or preheated or non-preheated temperatures (0 to 1300°C) for (V)PSA, to the desired / required temperature. Useful techniques are known for this purpose. Advantageously, electrical energy, in particular "green" or renewable electrical energy, can be used for this purpose, for example by resistive heating and / or plasma techniques.

[0083] Additionally, the reducing gas can be produced in any suitable manner, such as in a CO removal plant, for example, an amine-type adsorber starting from blast furnace gas, basic oxygen furnace gas, a PSA or VPSA, or others that can enhance CO separation by using a sorption-enhanced water-gas shift reactor. The reducing gas can also be the hydrogen-rich stream of a hydrogen removal plant.

[0084] Additionally, as noted above, the use of pure hydrogen gas as the reducing gas, or a mixture of N2 and H2 resulting from the decomposition of ammonia (or the decomposition of methanol and / or ethanol) is also expressly contemplated.

[0085] In the method disclosed herein, it is possible in principle to reach a coke rate of about 100 kg / tHM by almost completely removing nitrogen from the gas passing through the blast furnace and injecting the gas into the blast furnace at about flame temperature.

[0086] Instead of heating the synthesis gas injected into the tuyere, it is also possible to supply power directly to the blast furnace, for example by using plasma torches, electrodes immersed directly in the blast furnace, induction heating, etc.

[0087] It is particularly beneficial to reprocess a portion of the blast furnace top gas in a reformer, PSA, VPSA, CO2 removal plant, etc., to produce a reducing gas having an appropriate ratio of reductant to oxidant. The method considers various processes for producing reducing gas and injecting it, along with hydrogen and / or cracked ammonia, into the blast furnace at the shaft and tuyere levels.

[0088] It is also conceivable to use part of the blast furnace top gas as heating fuel for synthesis gas production. Only a small part of the blast furnace top gas can leave the blast furnace plant, which represents a high efficiency.

[0089] For permeability reasons, coke rates below 90 kg / tHM may not be achievable, but with the process of the present invention coke rates significantly below 200 kg / tHM can be reached.

[0090] As explained above, the main reason for injecting a portion of the reducing gas at the bottom of the furnace shaft rather than at the tuyere level is permeability issues. In fact, reducing the coke rate to a minimum level reduces the area through which the ascending gas passes in the cohesive zone. This increases gas velocity and pressure drop in the cohesive zone and upper dripping zone, potentially leading to abnormalities in the radial and circumferential gas distribution. Therefore, it is very important to reduce the gas volume in the tuyere and bosch zone, which is achieved by partially injecting the reducing gas at the shaft level. It is also advantageous to reduce the density and viscosity of the reducing gas. This can be achieved by using a hydrogen-rich reducing gas, which may or may not be enriched with additional hydrogen and has a very low density and viscosity, resulting in less pressure drop and lower gas velocity.

[0091] This process still uses some coke, and reforming of recycled furnace gas may require methane, etc. Further CO2 reductions can be achieved when methanation of CO and / or CO2-containing gases, such as blast furnace top gas and / or basic oxygen furnace gas, is used to produce natural gas. As an alternative to natural gas, the methane produced by methanation can also be employed to further reduce CO2 emissions.

[0092] Finally, the method may also include capturing CO2 from the reformer / heater flue gas or any other steel plant process gases for use or storage to further reduce overall CO2 emissions.

[0093] Case study: Reducing gas usage in blast furnaces

[0094] To better illustrate the present invention, several cases were investigated in more depth, the details of each case are shown in Table 2 below.

[0095] Case 1 and Case 2 are blast furnaces currently operating at crude coke rates of 255 kg / tHM and 205 kg / tHM, respectively.

[0096] Cases 3 and 4 are for a blast furnace with hot H2 injected into the tuyere without and with hot hydrogen injection into the shaft, respectively.

[0097] Cases 5 and 6 relate to new furnaces with superheated syngas injection at the tuyere level of about 180 kg / tHM and about 110 kg / tHM.

[0098] Cases 7 and 8 relate to new furnaces using superheated syngas injection at the tuyere level of about 180 kg / tHM and about 100 kg / tHM, plus superheated syngas injection into the shaft.

[0099] Case 1 represents a typical well-operated blast furnace with high pulverized coal injection (PCI), of which there are several found around the world, especially in Europe. PCI can reduce the lump or coke rate to a value of about 250 kg / tHM.

[0100] As can be seen, this furnace produces approximately 235 Nm3 per tonne of molten iron (tHM). 3 of oxygen, some of which is supplied from heated air and some of which comes from oxygen enrichment with pure oxygen supplied by an air separation plant.

[0101] This oxygen enrichment is necessary because a certain flame temperature is necessary for the blast furnace to operate properly. The flame temperature effectively ensures that the reduced ore melts and that the injected coal can burn within the orbit. At high PCI, the required flame temperature is approximately 2200°C.

[0102] In this case, natural draft cannot be completely eliminated, since a certain gas volume is required to ensure sufficient latent heat to provide the energy for heating and reducing the ore in the furnace shaft.

[0103] Case 2 represents a typical blast furnace that reaches exceptionally high PCI injection. Such operation has already been maintained for long production periods of several months. However, this operation is very difficult and requires high operating technology and very good raw materials, especially high-quality, expensive coke. It is important to note that in this case, a crude coke rate of 205 kg / tHM has already been reached.

[0104] Comparing the injection conditions at the tuyere, it can be seen that oxygen enrichment had to be further increased, but overall the conditions at the tuyere, hot blast temperature and gas volumetric flow rate did not change dramatically.

[0105] Neither of these operations is of course desirable if one wants to reduce CO2 emissions from molten iron production, as the energy and reductant inputs are all coal-based.

[0106] Case 3 and Case 4: In these cases, we analyzed blast furnace operations using high hydrogen injection rates to reduce some of the energy and reductant input from coal and use CO2-free hydrogen instead.

[0107] It is known that hydrogen cannot be injected at low temperatures through the tuyere together with oxygen-enriched hot blast, limiting the maximum hydrogen utilization rate to less than 30 kg / tHM.

[0108] Therefore, hydrogen addition requires modification: it needs to be injected at high temperature either at the tuyere level only or at both the tuyere and shaft level.

[0109] The inventors assume that the injection temperatures will be 950°C at the shaft level and 1200°C at the tuyere level, which are generally achievable when using conventional heat exchangers or regenerative heaters.

[0110] At the tuyere level, low-temperature oxygen must be added to burn the coke, in order to reach the flame temperature required for ore melting. From furnaces not using PCI injection, it is known that in this case the flame temperature can be reduced to a minimum of about 1800°C, always requiring a sufficient flow rate to provide sufficient energy for melting the reduced ore and for heating and reducing the ore in the shaft of the blast furnace.

[0111] As can be seen, the oxygen injection at the tuyeres was approximately 240 Nm 3 / tHM to 150Nm 3 / tHM and 180Nm 3 / tHM. Therefore, less carbon is burned in the tuyere. However, as there is no carbon available from PCI injection, more coke needs to be burned in the tuyere, and the coke rate increases, similar to Cases 1 and 2.

[0112] When using hydrogen in a blast furnace, additional coal / coke is required, so this contradiction with the need to reduce CO2 emissions cannot be overcome using conventional methods.

[0113] In addition, pure H2 injection, with and without shaft injection, yielded 1070 and 1280 Nm3 per tonne of molten iron, respectively, in both cases. 3 This means that a huge amount of hydrogen is required. 3 This far exceeds the hydrogen requirements of other production routes, such as direct reduction processes, which require 1000 tonnes of hydrogen per tonne. Furthermore, the coke ratios required in these cases are too high to be of any interest.

[0114] To overcome this problem, the inventors propose to inject synthesis gas into the blast furnace at superheated temperatures, with or without pure hydrogen addition.

[0115] Heating can be achieved, for example, by a plasma torch.

[0116] Cases 5 and 6: In these cases, superheating the gas injected at tuyere level has the advantage that we do not need to burn coke with oxygen to ensure the temperature level at the tuyere required to dissolve the reduced ore.

[0117] Cases 7 and 8: In these cases, additional syngas is injected into the shaft compared to Cases 5 and 6. We propose to operate the furnace by partially injecting gas into the shaft of the furnace, which allows the temperature level required for melting to be provided while reducing the electrical energy required for the plasma torch. Furthermore, with shaft injection, less gas needs to pass through the high-resistance cohesive zone region.

[0118] In contrast to Cases 7 and 8, in Cases 5 and 6, all the reducing gas required for operation must pass through the tuyeres, which means that it passes through the dripping zone and the cohesive zone, leading to flooding and hanging problems, respectively. Furthermore, in Cases 5 and 6, there is no way to avoid the inner wall channeling phenomenon mentioned above.

[0119] By operating the blast furnace as described herein, it is possible to actually reach the very low coke rates shown in Cases 7 and 8, i.e., coke rates of about 180 kg / tHM and about 100 kg / tHM, respectively.

[0120] Furthermore, the use of pure hydrogen is also very low, at 440 Nm3 / tHM at 100 kg / tHM.

[0121] This can be achieved, for example, by recycling blast furnace top gas back into the blast furnace. To do this, the H2O and CO2 content must be reduced. H2O can be easily reduced by cooling and condensation. CO2 removal is, for some reason, more complicated, and various methods have been proposed, including PSA, VPSA, and reforming CO2 with hydrocarbons to produce CO and H2.

[0122] In this example, natural gas reforming is used.

[0123] Such reforming can be carried out catalytically at temperatures of about 950°C, or without a catalyst in regenerative reformer types at elevated temperatures above 1100°C. The latter type is well suited to preparing gas at the tuyere level, as very high temperatures are desirable, especially at this level.

[0124] Also, when the gas is reformed at high temperatures, the degree of reduction of the gas can be made very high, with (CO + H2) / (CO2 + H2O) > 7, preferably > 8, and more preferably > 9. Since all the CO2 and H2O in the gas consumes coke in the orbit, a high degree of reduction is very important to achieve a low coke ratio.

[0125] [Table 2]

[0126] The volumetric flow rates of these gases are summarized in Table 3 below. [Table 3]

[0127] Coke consumption

[0128] Coke in BF is consumed by loss of solution reactions in the shaft, carbonization, direct reduction in the liquid state (above the dripping zone), and coke gasification / combustion in the tuyeres. Additionally, a small amount of coke fines is emitted into the dust during furnace charging.

[0129] Table 4 below shows for all cases the amount of coke consumed by the above mentioned measures (coke redistribution). [Table 4]

[0130] It can be seen that the coke consumption due to direct reduction in the liquid state is significantly lower in the new furnace conditions. This is because the iron load in the shaft is significantly reduced due to the extremely high reducing power (H2 + CO) in the furnace. Therefore, less FeO is reduced to Fe through direct reduction and liquor loss reactions. In cases 5 to 8, the coke consumption due to direct reduction is less than 20 kg / tHM, while it exceeds 70 kg / tHM in the conventional furnace. It can also be seen that in cases 7 and 8, the reducing gas injected into the shaft limits the coke consumption due to liquor loss, resulting in less chemical attack on the coke. Therefore, it is believed that the injection of reducing gas does not lead to an increase in the coke quality requirements in the new furnace cases.

[0131] Furthermore, because the superheated reducing gas brings a significant amount of heat energy to the blast furnace, the amount of coke required to be burned in the tuyere is reduced. Nevertheless, our reducing gas contains small amounts of H2O and CO2. These gases are converted to CO and H2 by reaction with carbon in the orbital region. Therefore, some of the coke is consumed in this region. This can be seen by comparing Cases 7 and 8. A significant portion of the coke is gasified (instead of being burned) by the injection of very hot reducing gas, thereby contributing to the formation and maintenance of orbits, even with a very low ratio of injected oxygen.

[0132] What has been described here shows how the coke rate can be reduced to very low levels using superheated reducing gas injected into the tuyeres and hot reducing gas at shaft level. The only thing that reducing gas cannot reduce is carbonization.

[0133] Detailed description of flooding and pressure drop in the fusion (melting) zone:

[0134] The purpose of this description is to show the relative, not absolute, changes in the flooding phenomenon and pressure drop in the dripping zone as well as at the entrance to the cohesive zone when changing from high coke rate blast furnace operation to low coke rate blast furnace operation.

[0135] The following dimensionless parameters are used for flooding:

[0136] The dimensionless parameters of the Matsu-ura and Ohno diagram, as well as the variables and units used in the calculations, are shown below as parameters (1) and (2):

[0137] Dimensionless pressure drop: JPEG2025529131000007.jpg20114(1)

[0138] ΔP, gas pressure drop between two points (Pa); ΔL, measured bed length ΔPd (m); ρl, liquid density (kg / m 3 );g, gravitational acceleration (m / s 2 ).

[0139] Dimensionless irrigation density: JPEG2025529131000008.jpg25114(2) σ, liquid surface tension (N / m); ρl, liquid density (kg / m 3 ), μ, liquid viscosity (Pa·s); ε, porosity (-); dp, particle harmonic diameter (m); u, liquid surface velocity based on empty column (m / s); θ, liquid contact angle with respect to solid (°). In all cases, the liquid considered was slag. Flooding occurs first in the slag, as it is much more viscous and less dense than the liquid iron.

[0140] In the first term of parameter (1), the dimensionless pressure drop, only the pressure drop ΔP depends on the gas properties.

[0141] In the second term, parameter (2), the dimensionless perfusion density, there is no parameter that depends directly on the gas properties, but only indirectly through the coke particle porosity and coke particle size.

[0142] In fact, increasing the flow rate and concentration of reducing agents (H2 and CO) in the gas reduces the coke consumption due to indirect reduction in the shaft (via the Boudouard reaction) and direct reduction in the dripping zone. Therefore, the coke particles in the cohesive zone and, more importantly, the dripping zone, have a larger diameter in these regions (because they are less consumed by the direct reduction reaction). See Table 4, which shows the coke redistribution in various cases. The larger the diameter, the larger the voids. Therefore, as a consequence, the dimensionless irrigation density decreases.

[0143] It is known that low values ​​of dimensionless perfusion density can result in high dimensionless pressure drop.

[0144] Depends directly on the pressure drop, i.e. the gas phase Return to JPEG2025529131000009.jpg17114.

[0145] In practice, this parameter is usually calculated using the Ergin formula: JPEG2025529131000010.jpg22114(3)

[0146] The first term in this equation is a laminar term, which can be neglected compared to the second turbulent term under the conditions of the cohesive and dripping zones.

[0147] So, to a good approximation, we can write: TIFF2025529131000011.tif16114(4)

[0148] As already mentioned, particle size (Dp) and porosity (ε) are positively affected by high fluxes and concentrations of H2 and CO.

[0149] Thus, always to be on the safe side, we can further simplify the following relationship: TIFF2025529131000012.tif17114(5)

[0150] The worst case scenario for a decrease in coke rate is the entry from the dripping zone into the cohesive zone, since the free passage of gas is lowest here. The velocity of gas passing through the cohesive zone can be estimated as the gas volumetric flow rate divided by the free cross section of the cohesive zone coke layer, so: TIFF2025529131000013.tif14114(6)

[0151] It can be said approximately that the free cross section is proportional to the coke rate, especially if the coke layer thickness does not change, so: TIFF2025529131000014.tif17114(7)

[0152] Embodiments of the present invention:

[0153] Blast furnaces are known to have already been successfully operated at crude coke rates below 210 kg / tHM using a high oxygen-enriched hot blast (high temperature air) supply and high pulverized coal injection rates.

[0154] The oxygen provides the energy to heat the tuyere gases to the high temperature levels required to melt the reduced ore in the orbits by consuming / burning the injected coal and coke.

[0155] To reduce CO2 emissions from blast furnaces, we want to eliminate injected coal and reduce the coke rate as much as possible.

[0156] For this reason, the amount of total oxygen injected into the tuyere should be kept at a low level, preferably 120 Nm 3 / tHM less than 112Nm 3 should be reduced to less than / tHM.

[0157] If one wishes to maintain typical orbital temperatures of 1800°C to 2600°C, the tuyere gas volumetric flow rate can be reduced slightly by about 20% to provide the energy to melt the reduced ore at a higher temperature level.

[0158] In current process proposals, reducing gas is no longer produced inside the raceways of the blast furnace, or at least only to a small extent, so that the reducing gas must be produced externally and fed to the furnace.

[0159] Table 4 shows the total mass flow injected into the furnace for all investigated cases. It is clear that this value is significantly lower in the new furnace compared to the conventional furnace due to the amount of H2 in the gas. The composition of the gas injected into the tuyere is shown in Table 6 for all cases.

[0160] Therefore, in order not to exceed the permissible hydrodynamic conditions of the cohesive zone, we argue that this can only be reached if the mass flow of reducing gas injected into the tuyere is kept below 800 kg / tHM, e.g., below 700 kg / tHM (see Table 5).

[0161] To do so, the hydrogen content of the gas injected at the tuyere level must be as high as 30%. It should be mentioned that although the total mass flow in the case of pure H2 (100%) is lower than in our case, the coke is as high as 274 kg / tHM and 324 kg / tHM.

[0162] [Table 5]

[0163] [Table 6]

[0164] To estimate the effect of such lower coke rates on the cohesive zone in terms of pressure drop, parameters of the gas entering the cohesive zone are needed, which is the result of the gas injected into the tuyere, coke combustion (when O2 is injected), coke gasification in the tuyere (when H2O and CO2 are present), and the final reduction reaction in the liquid state to produce CO (FeO(l) + C(s) → Fe(l) + CO).

[0165] In the new furnaces (Case 7 and Case 8), iron ore is reduced to nearly 100% mainly by the high reducing power of gas injected into the shaft and tuyeres, and is reduced to a limit by final reduction and coke combustion. Therefore, the amount of gas passing through the cohesive zone is significantly less in the new furnaces.

[0166] [Table 7]

[0167] To estimate the pressure drop across the CZ, we assumed that the ore layer was impenetrable. Furthermore, it is believed that some of the molten slag penetrates the coke layer in the CZ, thereby occupying part of its height. Therefore, this coke-ore interface layer is also considered to be of impenetrable thickness. That is, all the ascending gas can only pass through the remaining thickness of the CZ coke layer (total coke layer height - coke-ore interface layer height).

[0168] Therefore, the thickness of the coke layer excluding the interface layer is generally about 15 cm in operating BFs (Case 1 and Case 2). The thickness of the interface layer between the coke and the ore is assumed to be about 4 cm. Since the (effective) coke layer thickness is an important factor for stable furnace operation, it is preferable to keep this value constant in all cases.

[0169] As previously mentioned, pressure drop is a function of the density and velocity (volumetric flow rate and composition) of the ascending gas.

[0170] As can be seen from Table 4, the pressure drop in the CZ in Case 2 is significantly larger than that in Case 1 due to the lower coke rate.

[0171] The new furnace with a coke rate of 180 kg / tHM can operate well because the bosh gas can pass through the CZ much more smoothly. However, it appears difficult to reduce the coke rate to the final value of 100 kg / tHM without shaft injection due to the rather high pressure drop in the CZ. This means that the risk of flooding is high in Case 6.

[0172] This problem can be overcome by increasing the blast pressure. Higher blast pressure increases density and reduces the volume of gas entering the furnace. Since pressure drop is related to the square of velocity, the effect of velocity on pressure drop is much greater than that of density. TIFF2025529131000018.tif16114(Equation (5)). However, higher pressures require more expensive mechanical equipment and higher electrical energy demands.

[0173] However, this issue can be alleviated by shaft injection, which reduces the volumetric flow rate of injected gas into the tuyere, leading to a lower pressure drop. It can be clearly seen that the pressure drop in Case 8 (new furnace) is even lower than that in Case 2.

[0174] Furthermore, the new furnace has lower pressure drops in the CZ and dripping zone, which allows for an increase in production rate. To achieve the pressure drop level of the conventional BF (Case 2), the production rate can be increased by 15%. Therefore, Case 8 also proves the advantage of shaft injection.

[0175] Table 8 below shows the pressure drop at low and high production rates for Case 2 compared to Case 8. [Table 8]

[0176] Electric heating

[0177] An electrically driven heater can be employed to efficiently heat the (first) reducing gas to achieve the required temperature in the smelting furnace. Advantageously, the gas in a plasma state can be used as the heating means.

[0178] Electrode-based plasma torches can function as electrically powered heaters. The plasma is ignited on the surfaces of at least two electrodes. The electrodes can be made of graphite. At least one of the electrodes is at a high potential and at least one of the electrodes is at a low potential. Direct current and three-phase AC plasma torches are electrode-based plasma torches.

[0179] In addition to electrode-based plasma torches, there are also electrodeless plasma torches. In the latter, the plasma is ignited inductively, so no electrode is required. Classical electrodeless plasma torches include microwave (MW) plasma and radio frequency (RF) plasma. RF plasma is usually called inductively coupled plasma (ICP).

[0180] Direct current (DC) plasma torches have a low volumetric emission.

[0181] Alternating current (AC) plasma torches, especially three-phase AC plasma torches, have a high volumetric discharge, but feature other advantages: the plasma is confined to the ignition area, facilitating better control of the plasma position. Due to the AC and therefore cyclical operating mode, the electrode cools naturally, limiting electrode erosion and extending its lifespan. AC plasma torches do not require swirling gas or magnetic coils for plasma stabilization, as do DC plasma torches, making the torch design less complex.

[0182] A DC plasma torch can have two or more electrodes (e.g., 2, 4, 6, 8, 12, 14, 16, 18, 20). The more electrodes there are, the better the control of the plasma and the higher the power output of the plasma torch can be.

[0183] AC plasma torches, particularly three-phase AC plasma torches, can have a number of electrodes in multiples of three (e.g., 3, 6, 9, 12, 15, 18, 21, or more electrodes). The more electrodes there are, the better the control of the plasma and the higher the power output of the plasma torch can be.

[0184] Plasma torches, in particular DC plasma torches, and / or AC plasma and / or three-phase AC plasma torches, with a power output of 1 MW to 10 MW, preferably 2 MW to 6 MW, most preferably 4 MW to 5 MW, can be employed in the furnace as defined above.

[0185] The plasma torch may be integrated with one or more gas injectors.

[0186] Preferably, one power supply powers 1 to 10, 1 to 5, 1 to 3, or 1 of the at least one plasma torch.

[0187] To ensure stable plasma operation, power supplies are often designed with a reserve capacity. This reserve capacity can be three, preferably two, or even one or five times the plasma power required to operate the plasma torch. Using multiple power supplies under 30 MW, 20 MW, and / or 10 MW to power multiple plasma torches (one power supply driving one or more plasma torches) is preferable to using a single dedicated power supply with a total capacity equal to or greater than the combined capacity of all the lower-capacity power supplies. In the former case, the flicker imposed on the grid by fluctuations in the operation of the plasma torches is much smaller than in the latter case. Furthermore, using multiple power supplies under 30 MW, 20 MW, or 10 MW improves controllability and flexibility. Even if a power supply fluctuates or crashes, the system remains intact, and the power input of the failed power supply can be collectively supplied by other power sources, allowing the furnace to continue operating without serious problems. Furthermore, one or more reserve power supplies can be installed online, ensuring steady operation at full power by switching to the reserve power supply in the event of a primary power supply failure. Repairs can be carried out during the next scheduled maintenance shift, so no production loss occurs. However, a large number of power supplies increases costs, power losses, and space requirements, so it is important to select the optimal number of power supply units.

[0188] In AC plasma torches, particularly three-phase AC plasma torches, the electrodes may be rod-shaped. When the plasma is turned on, the sides of the electrodes placed in the plasma ignition zone erode, shortening the electrode's length. The plasma torch is equipped with a mechanism that maintains a constant inter-electrode gap in the plasma ignition zone by moving the electrodes inward toward the plasma ignition zone. After a predefined minimum length is exceeded, the mechanism can replace or modify the electrodes. In an embodiment, the inter-electrode gap can be adjusted between 0 and 100 mm, for example, between 5 and 50 mm, or approximately 40 mm.

[0189] Electrode modification is accomplished by connecting, for example, by screwing a new electrode onto the backside of the old / used electrode (the side opposite the side of the electrode placed in the plasma ignition area). Attachment of the new electrode to the old electrode is performed by an electrode gripper while the torch is in operation.

[0190] When graphite electrodes are gradually eroded and worn away by plasma operation, another possibility for electrode repair is the use of a carbon-based paste. Carbon paste, typically a mixture of graphite and a binder, may be applied to the worn or worn portion of the electrode. This paste replenishes the carbon content, extending the electrode's lifespan and helping to maintain efficient conductivity and heat transfer during plasma operation. Adding carbon paste to repair graphite electrodes is typically accomplished by applying a column of electrode paste to the worn portion of the graphite electrode using equipment designed to repair electrodes without interrupting the plasma process. The carbon-based paste-containing equipment gradually forces the paste into the electrode column, filling voids left by the worn electrode material and restoring the carbon content. This allows for controlled and precise addition of carbon paste, ensuring that electrode performance and efficiency are maintained throughout plasma operation, thereby extending the electrode's operating life and contributing to the overall effectiveness of plasma operation.

[0191] In a DC plasma torch, the electrode may have a tubular shape. During operation, the tubular sidewall in the plasma ignition region erodes, reducing the electrode's thickness. A plasma torch electrode replacement device replaces a broken electrode with a new one in the plasma torch. The replacement of the used electrode with a new one is achieved by a further electrode gripping device.

[0192] The mechanism of the electrode replacement system can be equipped with a magazine for new electrodes and a magazine for used electrodes, so that the plasma torch can operate without manual operation for long periods of time.

[0193] In DC plasma torches, the plasma is controlled by adjusting electrical operating parameters. In three-phase AC plasma torches, plasma control is based on a camera that continuously captures plasma images. The plasma properties (i.e., luminosity, shape, diffusivity, etc.) shown in these images are benchmarked using associated software against plasma images that show the properties of the plasma at steady state. Changes (i.e., electrode gap, voltage amplitude, etc.) are then made to keep the plasma in a stable regime.

[0194] In some embodiments, the gas velocity across a plasma heater comprising a plasma torch can be between 10 m / s and 120 m / s, preferably between 20 m / s and 50 m / s. The incoming gas stream reaching the plasma heater can be split into at least two streams: a first stream flowing centrally through the arc generated by the plasma torch and a second stream flowing circumferentially around the arc. Both streams can have substantially the same velocity and / or fluid dynamics. However, the two streams preferably have different velocities and fluid dynamics; for example, the central stream across the arc is preferably a low-speed (5-60 m / s) stream with as little turbulence as possible, while the peripheral stream is preferably a high-speed (30-200 m / s) stream and may be arranged as a vortex.

[0195] In some preferred embodiments, the central stream flows through the plasma arc and is heated to a very high temperature, and the second stream is injected just downstream of the plasma arc and oriented to protect the refractory-lined walls of the plasma burner chamber of the plasma torch from the heat of the hot central stream, thereby advantageously reducing the heat load on the wall lining.

[0196] Detailed Description of the Embodiments

[0197] FIG. 1 illustrates an advantageous embodiment of a smelting furnace facility according to some aspects of the present invention, such as a blast furnace facility modified to operate in accordance with the present invention.

[0198] The (improved) blast furnace installation comprises a blast furnace 10 having a blast branch pipe 21 fed by conventional tuyere and bustle pipes 20. However, unlike conventional blast furnaces, the bustle pipes 20 feed a reducing gas A into the first blast furnace 10 through the blast branch pipes 21 and tuyere. Additionally, a second reducing gas B is fed at shaft level through a number of injectors (not shown), which are fed by a ring pipe 25.

[0199] The first reducing gas A and the second reducing gas B preferably comprise reformed gases obtained by reforming the top gas D of a blast furnace or other gases from a metallurgical plant. Optionally, H2 can be added to the second reducing gas B to specifically increase the hydrogen content of the second reducing gas or its temperature can be adapted, e.g., cooled to a desired temperature. The reforming can be carried out in any suitable reformer 40 or device operating as such, for example a regenerative heat exchanger as shown in FIG. 1, in the presence of HO and / or natural gas (NG) or any other suitable source. If necessary, hydrogen can be added to the reformer 40.

[0200] Prior to reforming, the top gas D is preferably washed in a top gas scrubber 50 to remove solid particles, thereby providing a washed top gas C. If necessary, the top gas D or the washed top gas C can be subjected to further treatment steps, such as (partial) removal of certain components, e.g., HO, chlorine, heavy metals, sulfur components such as COS, before entering the reformer 40. The cleaned top gas C can also be added directly (i.e., without being reformed) to the second reducing gas B.

[0201] The first reducing gas A is heated to a temperature above 1600°C before being injected into the blast furnace 10 through the tuyere via the blast pipe 21. This (additional) heating (or part of this heating) can be carried out through a (resistance) heating device 30 before entering the bustle pipe 20. However, the first reducing gas A is preferably heated to the desired temperature only immediately before being injected into the blast furnace 10, for example by a plasma torch (not shown) installed in the blast pipe 21, such as a blowpipe.

[0202] If necessary or desired, small amounts of oxygen E can be added at the tuyere level, such as to form and maintain orbital air gaps in the tuyere 21 within the blast furnace 10. (Optionally) the oxygen E is preferably added at a fairly low temperature (compared to the first reducing gas) to allow for cooling of the tuyere 122 (FIG. 2).

[0203] Figure 2 shows a schematic diagram of a possible embodiment of an electric heater useful in the context of the present invention. In this embodiment, three-electrode plasma torches 1213 (only two are shown due to the cutaway view) are disposed within the blowpipe 1211 of the blowpipe 121, with their electrodes 1214 reaching into the central duct of the blowpipe 1211, which preferably includes a refractory lining 1212. In Figure 2, the blowpipe 121 is fluidly connected to a tuyere 122 disposed within the wall of the smelting furnace (not shown), with the nose 1221 of the tuyere 122 reaching into the furnace. An oxygen port 1222 is advantageously disposed within the tuyere 122 mechanism for injecting (preferably cryogenic) oxygen, as further disclosed above.

[0204] Figure 3 is a schematic (semi-)sectional view of an operating blast furnace, including stacked layers of coke and iron ore fed from the top of the furnace. Figure 3 also shows a detailed view of the layers within the cohesive zone. A first reducing gas, A, is injected at the tuyere level, thereby forming a trajectory due to the gas velocity and direct gasification of the coke. The resulting gas rises within the furnace and must pass through the coke layer within the cohesive zone, while the softened, molten iron (ore) layer within the cohesive zone becomes essentially impermeable to gas. Injection of a second reducing gas, B, pushes the rising gas toward the center of the furnace, thereby largely preventing the wall channeling effect described above. [Explanation of symbols]

[0205] Reference table 10 “High” furnace 20 Bustle tube of first injector device 21 First injector device air supply pipe 25 Ring pipe of second injector device 30 Heating Unit 40 Reformer 50 Top gas cleaning unit A. First reducing gas B Second reducing gas C Cleaned furnace gas D Furnace top gas E (Optional)O2 121 Air branch pipe 1211 Blowpipe 1212 Refractory lining 1213 Plasma Torch 1214 Electrode 122 Tuyere 1221 Tuyere Nose 1222 Oxygen Port

Claims

1. A method for operating smelting furnace equipment, particularly blast furnace equipment, - A step of supplying coke, iron oxide-containing and other iron-containing materials, and fluxing agents as needed, to the top of the smelting furnace, - A step of injecting a first reducing gas containing hydrogen at the tuyer level of the smelting furnace, wherein the first reducing gas is heated to a temperature exceeding 1600°C, - A step of injecting a second reducing gas at the lower shaft level of the smelting furnace within the gas solid reduction zone of ferrous oxide above the fusion zone, Includes, The coke is supplied at a lump coke ratio of less than 220 kg / tHM, preferably less than 200 kg / tHM, and more preferably less than 180 kg / tHM, and the density of the first reducing gas is 0.80 kg / Nm³. ３ Less than 0.60 kg / Nm ３ Less than 0.30 kg / Nm ３ A method that is less than.

2. At the tuyere level of the smelting furnace, 120 Nm ３ Less than / tHM, preferably 112Nm ３ The further step includes injecting oxygen at a ratio of less than / tHM, The method according to claim 1, wherein the temperature of the injected oxygen is preferably less than 600°C, more preferably less than 400°C.

3. The method according to claim 1, wherein the first reducing gas is injected at the tuyere level in a total mass flow of less than 800 kg / tHM, preferably less than 775 kg / tHM, and more preferably less than 750 kg / tHM.

4. The first reducing gas and / or the second reducing gas is a gas obtained by reforming a reforming process, particularly a gas containing coke oven gas, natural gas, biogas, and / or other hydrocarbons, into H ２ O, CO ２ , or CO ２ and / or H ２ O-containing gas, more preferably a gas generated by reforming steel plant off-gas such as blast furnace top gas, basic oxygen furnace gas, and / or open hearth furnace gas. The method according to claim 1, comprising the gas.

5. The first reducing gas and / or the second reducing gas are absorbed by, for example, monoethanolamine (MEA), membrane separation, pressure swing adsorption (PSA), or vacuum pressure swing adsorption (VPSA) of CO2. ２ The method according to claim 1, comprising a gas produced by applying a separation technique to a hydrogen and / or CO-rich gas, more preferably to a steel plant gas such as a smelting furnace top gas, a basic oxygen gas, and / or an oxygen blast furnace gas.

6. The method according to claim 1, wherein the first reducing gas has a hydrogen content of about 30% by volume, preferably more than 40% by volume, and more preferably more than 50% by volume.

7. The method according to claim 1, wherein the first reducing gas is injected at a temperature of 1600°C to 2600°C, more preferably at a temperature above 1800°C, and most preferably at a temperature above 2000°C.

8. The method according to any one of claims 1 to 7, wherein the first reducing gas is heated, preferably in the duct and / or tuyeres, by one or more electric heaters, most preferably by one or more plasma torches, before being injected into the smelting furnace.

9. The method according to claim 8, wherein the first reducing gas is heated by one or more plasma torches placed in the blowpipe of the vent pipe, the plasma torches being electrode-based or electrodeless plasma torches, preferably selected from inductive ignition plasma torches, microwave plasma torches, high-frequency plasma torches, or a combination thereof.

10. The method according to claim 9, wherein the one or more plasma torches are DC plasma torches and / or AC plasma torches and / or three-phase AC plasma torches, and the plasma torches generally have a power rating of 1 MW to 10 MW, preferably 2 MW to 6 MW, most preferably 4 MW to 5 MW.

11. The first and / or second reducing gas has a molar ratio (H) greater than 6, preferably greater than 7, and more preferably greater than 8. ２ +CO) / (H ２ O+CO ２ The method according to any one of claims 1 to 7, having )

12. The method according to any one of claims 1 to 7, wherein the second reducing gas has a hydrogen content of about 25% by volume, preferably more than 30% by volume, and more preferably more than 40% by volume.

13. The method according to any one of claims 1 to 7, wherein the second reducing gas is injected at a temperature of 800°C to 1200°C, more preferably at a temperature of less than 1100°C, and most preferably at a temperature of less than 1000°C.

14. The method according to any one of claims 1 to 7, wherein the pressure level of the smelting furnace at the tuyeres level is controlled to a value greater than 2 barg, preferably greater than 4 barg, and more preferably greater than 5 barg.

15. The method according to any one of claims 1 to 7, wherein the first reducing gas and the second reducing gas have a nitrogen content of less than 35 vol%, preferably less than 15 vol%, more preferably less than 10 vol%, and most preferably less than 5 vol%.

16. The method according to any one of claims 1 to 7, wherein the first and / or second reducing gas includes a gas resulting from the decomposition of ammonia.

17. The method according to any one of claims 1 to 7, wherein the coke is supplied in layers, and the height of each coke layer is at least 10 cm, preferably at least 12 cm, and more preferably at least 15 cm.

18. The method according to any one of claims 1 to 7, further comprising the step of adjusting the average reduction degree of the iron oxide-containing material reaching the fusion zone to a value greater than approximately 85%, by controlling the amount and / or composition of the second reducing gas injected at the shaft level as a function of the amount and / or composition of the first reducing gas injected at the tuyere level and / or the amount of oxygen injected at the tuyere level.

19. The method according to any one of claims 1 to 7, further comprising the step of reducing the channeling effect and flooding effect by controlling the furnace top pressure of the smelting furnace to a range of 1 to 10 bar, more preferably 2 to 7 bar, and most preferably 3 to 5 bar.

20. The method according to any one of claims 1 to 7, further comprising the step of reducing the inner wall channeling effect of the gas coming from the fusion zone by controlling the injection conditions of the second reducing gas, for example, the injection rate and / or ratio of the second reducing gas injected into the shaft of the smelting furnace.

21. The method according to any one of claims 1 to 7, further comprising the step of reducing the carbon dioxide content of off-gas and / or process gases containing any one or more carbon dioxide generated during operation by carbon capture and utilization (CCU) and / or carbon capture and storage (CCS).

22. The method according to any one of claims 1 to 7, further comprising the step of converting off-gas carbon dioxide containing any one or more carbon dioxide generated during operation into a synthetic fuel, for example, synthetic natural gas by methane production, or methanol and / or ethanol by methanol and / or ethanol production.

23. Smelting furnace equipment, especially blast furnace equipment, - A charging device configured to supply coke, iron oxide-containing and other iron-containing materials, and fluxing agents as needed, to the top of the smelting furnace, - A first injector device positioned at the tuyere level of the smelting furnace and configured to inject a first reducing gas containing hydrogen at a temperature exceeding 1600°C at the tuyere level of the smelting furnace, - A second injector device positioned at the shaft level of the smelting furnace and configured to inject a second reducing gas at the lower shaft level of the smelting furnace, within the gas solid reduction zone of ferrous oxide above the fusion zone, Equipped with, The charging apparatus is configured to supply coke at a lump coke ratio of less than approximately 220 kg / tHM, preferably less than approximately 200 kg / tHM, and more preferably less than approximately 180 kg / tHM. The first syringe device has a flow rate of approximately 0.80 kg / Nm ３ Less than, preferably about 0.60 kg / Nm ３ Less than, most preferably about 0.30 kg / Nm ３ The system is configured to inject the first reducing gas at a density of less than the specified density. The first injector device is a smelting furnace facility comprising an electric heating device configured to heat the first reducing gas to a temperature exceeding 1600°C.

24. The first syringe device further comprises an oxygen injection port device, the oxygen injection port device having a capacity of 120 Nm ３ Less than / tHM, preferably 112Nm ３ The smelting furnace equipment according to claim 23, configured to inject oxygen at the tuyeres level at a ratio of less than / tHM, wherein the temperature of the injected oxygen is preferably less than 600°C, more preferably less than 400°C.

25. The smelting furnace equipment according to claim 23, wherein the first injector device is configured to inject the first reducing gas at the tuyere level with a total mass flow of less than 800 kg / tHM, preferably less than 775 kg / tHM, and more preferably less than 750 kg / tHM.

26. The reforming process converts gases, particularly coke oven gas, biogas, natural gas, and / or other hydrocarbons, into H ２ O and / or CO ２ Or CO ２ and / or H ２ The smelting furnace apparatus according to claim 23, further comprising one or more reformers configured to produce a gas as a first and / or second reducing gas by reforming with a gas containing oxygen, more preferably with a steelmaking off-gas such as a smelting furnace top gas, a basic oxygen furnace gas, or an open-bath furnace gas.

27. CO2 absorption by monoethanolamine (MEA), membrane separation, pressure swing adsorption (PSA), or vacuum pressure swing adsorption (VPSA) ２ CO ２ The smelting furnace apparatus according to claim 23, further comprising one or more devices configured to separate and process the smelting furnace top gas, basic oxygen furnace gas, and / or open bath furnace gas.

28. The smelting furnace apparatus according to claim 23, further comprising a first hydrogen source and a first hydrogen content control device configured to adjust the hydrogen content of the first reducing gas to a value of more than 30 volume%, preferably more than 40 volume%, and more preferably more than 50 volume%.

29. The smelting furnace equipment according to claim 23, wherein the electric heating device of the first injector device is configured to heat the first reducing gas to a temperature of 1600°C to 2600°C, more preferably above 1800°C, and most preferably above 2000°C.

30. The smelting furnace apparatus according to any one of claims 23 to 29, comprising one or more electric resistance heaters and / or one or more plasma torches in the electric heating device.

31. The smelting furnace equipment according to claim 30, wherein the electric heating device comprises one or more plasma torches disposed in the blowpipe of the vent pipe, and the plasma torches are preferably electrode-based plasma torches or electrodeless plasma torches selected from induction ignition plasma torches, microwave plasma torches, high-frequency plasma torches, or combinations thereof.

32. The smelting furnace equipment according to claim 31, wherein the one or more plasma torches are DC plasma torches and / or AC plasma torches and / or three-phase AC plasma torches, and the plasma torches generally have a power rating of 1 MW to 10 MW, preferably 2 MW to 6 MW, most preferably 4 MW to 5 MW.

33. The smelting furnace apparatus according to any one of claims 23 to 29, further comprising a second hydrogen source and a second hydrogen content control device configured to adjust the hydrogen content of the second reducing gas to more than 25 volume%, preferably more than 30 volume%, and more preferably more than 40 volume%.

34. The smelting furnace equipment according to any one of claims 23 to 29, wherein the first injector device is configured to control the mass flow rate of the reducing gas injected into the smelting furnace at the tuyere level to 800 kg / tHM, preferably less than 775 kg / tHM, and more preferably less than 750 kg / tHM at a pressure level of more than 2 barg, preferably more than 4 barg, and more preferably more than 5 barg.

35. The smelting furnace apparatus according to any one of claims 23 to 29, further comprising a control unit configured to adjust the average reduction degree of the iron oxide-containing material reaching the fusion zone to a value greater than 85% by controlling the amount and / or composition of the second reducing gas injected at the shaft level through the second injector device as a function of the amount and / or composition of the first reducing gas injected at the tuyere level, and / or the amount of oxygen injected at the tuyere level through the oxygen injection port.

36. The smelting furnace equipment according to any one of claims 23 to 29, further comprising a carbon capture and utilization (CCU) unit and / or carbon capture and storage (CCS) unit downstream of at least one carbon dioxide-containing off-gas generating element in order to reduce the carbon dioxide content in the off-gas.

37. The smelting furnace apparatus according to any one of claims 23 to 29, further comprising a methane unit configured to convert carbon dioxide into synthetic natural gas and / or process gas, or any other apparatus for producing synthetic hydrocarbons such as methanol or ethanol.

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