Method for operating a steel mill

Abstract

To provide a method for operating a steelmaking plant which reduces the emission of gas affecting the climate in steel production, and at the same time, guarantees the overall observation of a production process against the background of efforts to maintain good economic efficiency in steel production.SOLUTION: The present invention relates to a method of operating a steelmaking plant using direct reduction of iron ore with hydrogen, for example in a blast furnace converter route, or with an electric steelmaking route downstream, preferably also with a secondary steelmaking route. To carry out the process, A) the reactant streams of the reactants supplied, B) the accompanying product streams of the accompanying products discharged and C) the energy streams of the energy utilized are balanced.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for operating a steel plant. [Background technology]

[0002] Various methods of operating a steel plant to produce steel are known. The most common method is still the so-called blast furnace-converter route, i.e., producing pig iron in a blast furnace from iron ore using coke, with partial addition of hydrogen in the form of H2 and / or CH4 along the way, and then further processing the pig iron to steel, possibly with the addition of scrap or other additives. However, the blast furnace-converter route has the disadvantage of being associated with high CO2 emissions.

[0003] In the context of efforts to reduce emissions of climate-impacting compounds, alternative methods are becoming increasingly important. For example, when operating steel plants, the direct reduction of iron ore with hydrogen, with downstream electric and oxygen steelmaking routes, is becoming increasingly important, particularly to avoid CO2 emissions. In this case, direct reduction is carried out using hydrogen as a reducing agent for the iron ore, which can be, for example, electrolytically produced hydrogen or hydrogen bound to methane.

[0004] Monitoring the release of climate-impacting gases and other substances is possible through known and practiced methods: determining the total amount of emissions occurring directly or indirectly at various stages of a product and considering the determined value as the so-called "carbon footprint." When CO2 is considered a climate-impacting gas, consideration is based on determining the CO2 emissions occurring directly or indirectly at various stages of a product. When monitoring the amount of CO or other gases, such as CH4 or NOx, or other substances, such as fine dust, occurring directly or indirectly at various stages of a product as a climate-impacting gas, consideration is based on identifying a CO2-equivalent value, which is a measure of the amount of CO2 equivalent required over a specific period, such as 100 years, for an equivalent average warming effect in the Earth's atmosphere. The feeding back of emissions of climate-impacting gases and other substances into a CO2-equivalent value has the advantage of allowing a good comparison of various emissions.

[0005] In the context of efforts to reduce climate-impacting gas emissions in steel production and at the same time maintain good economics in steel manufacturing, it is necessary to ensure comprehensive monitoring of the manufacturing process. Summary of the Invention [Problem to be solved by the invention]

[0006] The object of the present invention is to ensure, or at least facilitate, such comprehensive observation. [Means for solving the problem]

[0007] The above problem is solved by a method for operating a steel plant having the features of claim 1. DETAILED DESCRIPTION OF THE INVENTION

[0008] especially, a) Blast furnace / converter route method, or b) A method of direct reduction of iron ore with hydrogen can be used, with a downstream electric steelmaking route, preferably also a secondary steelmaking route.

[0009] The process is carried out by supplying starting materials and by supplying energy, during which intermediate products are formed in successive steps and with the discharge of accompanying products, and finally steel is obtained as the finished product.

[0010] According to the invention, in order to carry out the method, at least the following material flow balances are required: A) A balance of multiple starting material flows of the starting materials supplied; B) the balance of the multiple entrained product flows of the discharged entrained products, and C) A balance of multiple energy flows of utilized energy is performed.

[0011] To achieve this balance, a CO2 footprint value is determined for each observed starting material flow, each observed associated product flow, and each observed energy flow.

[0012] To distinguish between the various CO2 footprint values ​​formed, an initial CO2 footprint value is determined for each starting material flow and for each energy flow, and a connected CO2 footprint value is determined for each associated product flow. A total CO2 balance value (CO2-Gesamtbilanzwert) is formed from the sum of the CO2 footprint values. During the execution of the method, the CO2 footprint values ​​and the CO2 total balance value are continuously updated.

[0013] The term CO2 footprint value includes emissions of CO2 as CO2 equivalent and emissions of other gases and other substances that have an impact on the climate. The same applies to initial CO2 footprint value, connected CO2 footprint value and CO2 footprint value, which are always related not only to CO2 itself but also to the CO2 equivalent of other gases and substances that have an impact on the climate.

[0014] Balancing CO2 footprint values ​​refers to the observation of all material flows, particularly for each starting material, each accompanying material, and the energy used to operate a facility, from source to utilization, preferably until the end of its useful life, and the assignment of a CO2 footprint value to this material flow. In this case, the term CO2 footprint value means that for each material flow, the total amount of observed CO2 or CO2 equivalents associated with the material flow is balanced against a comparative amount. For example, for each material flow, the total amount of CO2 and CO2 equivalents emitted in kilograms for the production of one ton of a final product, such as hot-rolled steel, can be determined, and all production and other processing steps, including transportation, are observed. The balancing can be performed stepwise by creating a one-dimensional or multidimensional list containing each observed, preferably existing, material flow and assigning a CO2 footprint value to each observed, preferably existing, material flow. The CO2 total balance value is formed using the CO2 footprint values, and only one CO2 total balance value is assigned to the production of an end product, e.g., 1 ton of end product. This value is therefore a measure of the amount of CO2 emitted during the production of the end product. It is important that the CO2 total balance value is based on the sum of the CO2 footprint values ​​taken into account for each observed starting material flow, associated product flow, and energy flow, and is preferably continuously updated. This approach ensures, in particular, that CO2 emissions occurring in connected and upstream value chains can also be taken into account to form the CO2 total balance value. In particular, possible CO2 emissions can also be taken into account, so that, for example, linking CO2 throughout the entire process will have a positive effect on the CO2 total balance value.

[0015] According to the present invention, if the CO2 total balance value exceeds a predetermined CO2 footprint threshold, Supply of starting materials and / or It is contemplated that the energy supply will be adjusted to reduce the CO2 footprint value below the CO2 footprint threshold.

[0016] In other words, the CO2 total balance value is continuously or almost continuously, i.e. repeatedly, compared with the CO2 footprint threshold value, and if this threshold value is exceeded, the way in which the steel plant operating method is carried out is adjusted. This adjustment can be made in the supply of starting materials, the energy supply, or both. For example, from a predetermined selection of starting materials, each of which has a material-specific CO2 footprint value stored, adjustment can be made so that a sub-selection or a specific configuration of selection is made depending on the magnitude of the CO2 total balance value. Alternatively or additionally, adjustment can be made to change the energy supply in stages, so that the selection of the power supply is selected depending on the power production.

[0017] In a first variant of the method, the blast furnace converter route is used.

[0018] To carry out the method, A) In the blast furnace process, at least starting materials such as iron ore, coke, and air, particularly O2, are supplied, and in the converter process, at least starting materials such as calcium oxide and oxygen are supplied; B) As an associated product stream, at least CO2 and slag are emitted; C) Electrical energy is used to operate the equipment.

[0019] Starting from such an initial combination, an initial CO footprint is determined for each starting material flow and each energy flow. The starting point for determining the initial CO footprint of a starting material can be found, for example, on the basis of data in a database, or on the basis of CO footprint values ​​provided by a supplier, or on the basis of a chemical analysis carried out by oneself.

[0020] To determine the CO footprint connection value of the associated product flow specific to each associated substance, the amount of emitted CO, preferably also at least CO and / or other carbon compounds such as CH, is measured, or the change in the amount of emitted CO, preferably also at least CO and / or other carbon compounds such as CH, is measured, using CO measuring devices, and optionally additionally C measuring devices, located at one or more suitable locations in the steelmaking plant. The measuring devices are preferably used for measurements in the aggregate state of solids and / or liquids and / or gases. That is, the amount of CO, preferably also at least CO and / or other carbon compounds such as CH, emitted during the operation of the steelmaking plant is determined by direct measurement. The CO footprint connection value is determined from one or more measured values ​​obtained.

[0021] For slag, which is an associated material, further uses of the slag are taken into account in calculating the CO2 footprint connection value of the associated product flow. This may involve balancing the use of slag as a road paving material against the alternative use of other materials as road paving material that may have higher CO2 footprint values, which in this example may result in a negative CO2 footprint connection value for the associated material flow of slag.

[0022] Preferably, other associated substances are also taken into account, and the CO footprint connection value of the associated product flow is calculated taking into account the further use of one or more of the associated substances tar, sulfur, benzene, heat, steam.

[0023] In this example, the CO2 total balance value is determined, for example, aggregately from the CO2 footprint initial value and the CO2 footprint connected value.

[0024] In the above-described development, if the CO2 total balance value exceeds a predetermined threshold, for example, if the energy supply is switched to the use of available energy generated by a wind power plant and / or starting materials of the same value with a higher initial CO2 footprint are stored, for example, on the steelworks site, the selection of starting materials with a higher initial CO2 footprint for feeding the blast furnace / converter route is changed to the selection of starting materials with a lower initial CO2 footprint for feeding the blast furnace / converter route if the CO2 total balance value exceeds the predetermined threshold. In this way, for example, the monitoring of CO2 footprint values ​​can be used in real time or near real time to control the operation of the steelworks so that its CO2 total balance value is permanently below the predetermined threshold for all process chains, with the advantage that this can contribute to achieving the long-term goal of climate neutrality. That is, the steelworks is controlled, preferably optimized, by observing the CO2 footprint values ​​of all observed starting material flows, associated product flows, and energy flows as a whole, i.e., the CO2 total balance value.

[0025] Preferably, the control of the addition of starting materials is by measuring the weight of the starting material added, or by measuring the volumetric flow rate of the starting material being added, or Energy flow is measured by measuring the amount of work done by the energy flow, and the CO2 footprint value and CO2 total balance value are continuously updated based on the measured values.

[0026] Preferably, in the blast furnace process, The starting materials listed below: i) natural gas; ii) H2, iii) methane, and further providing at least one or more of: In this method variant, it is preferable to increase the proportion of natural gas and / or H in the starting material flow depending on the CO2 total balance value when the CO2 total balance value exceeds a predetermined CO2 footprint threshold. It is particularly preferable to increase the proportion of hydrogen-containing gases, methane, from biogas production, pyrolysis of synthesis gas from recycled feedstocks or biomass, in the total amount of said gases when the CO2 total balance value exceeds a second CO2 footprint threshold that is greater than the CO2 footprint threshold. This method variant is particularly advantageous in that CO2 emissions and / or emissions of other climate-impacting gases or substances are reduced first by providing a reducing gas; when the CO2 total balance value is higher than or above a higher threshold, i.e., the second CO2 footprint threshold, not only is the hydrogen-containing reducing gas selected to reduce CO2 emissions and, preferably, further reduce emissions of other climate-impacting gases, but also the source of hydrogen or the manner of production or extraction of hydrogen depends on the CO2 total balance value, within the scope of the previously selected use of the hydrogen itself. This method particularly advantageously achieves that both the selection of the reducing element and the selection of its origin or extraction are carried out in two successive steps, so that in the first step the origin of the hydrogen can be determined purely on economic grounds, and only in the second step does the economic basis take a back seat to observations directed at the CO2 total balance value.

[0027] In particular, the blast furnace converter route is equipped with the following measuring instruments: It may be contemplated to have one or more of the following instruments: a weighing instrument, an elemental analysis instrument (CHNS-O and / or FOES and / or ICP-OES), DCP, IR, concentration measurement, Wobbe index, GCMS, bomb calorimeter, conductivity measuring instrument, ammeter, current-voltage measuring instrument, gas amount measuring instrument, thermometer, viscosity measuring instrument, loss on ignition measuring instrument, humidity measuring instrument, C content measuring instrument for all aggregation states.

[0028] In a second variant of the process, direct reduction of iron ore with hydrogen is used with a downstream electric steelmaking route.

[0029] To carry out the method, A) at least starting iron ore and at least one starting H2, methane, natural gas, or other carbon-containing gas are added to a direct reduction facility to produce sponge iron; B) As an associated product flow, at least CO2 and preferably also H2O are discharged, C) Electrical energy is used to operate the equipment, An initial CO2 footprint is determined for each starting material and energy flow.

[0030] Similar to the approach described in relation to the blast furnace / converter route, an initial CO2 footprint of the starting material is determined based on data from a database or values ​​provided by the supplier.

[0031] The CO2 footprint connection value of the associated product flow for the associated substance CO2 is measured by measuring the amount of CO2 emitted or by measuring the change in the amount of CO2 emitted using a CO2 measurement device. Preferably, the CO2 footprint connection value of the associated product flow for the associated substances CO and CH4 is measured by measuring the amount of C emitted or by measuring the change in the amount of C emitted using a C measurement device.

[0032] The CO2 total balance value is determined in aggregate from the CO2 footprint initial value and the CO2 footprint connected value.

[0033] Similar to what has been described above in connection with the blast furnace / converter route, if the CO2 total balance value exceeds a certain threshold, the energy supply is switched to the use of energy from low-carbon production, for example renewable energy or nuclear energy.

[0034] Alternatively or additionally, starting materials of equal value with different initial CO2 footprints are stored intermediately, for example, on the steelworks site, and if the CO2 total balance value exceeds a predetermined threshold, the selection of starting materials with higher initial CO2 footprints for supply to the direct reduction facility or at another entry point in the production route is changed to the selection of starting materials with lower initial CO2 footprints for supply to the production route. This means that, when considered along the entire value chain, by storing starting materials with different initial CO2 footprints, a CO2-free starting material is prepared, which can be selected, if necessary, to be supplied to the process in order to reduce the CO2 total balance value below the predetermined threshold. This approach advantageously achieves the effect of permanently keeping the CO2 total balance value below the predetermined threshold.

[0035] Alternatively or additionally, it is possible to provide that, when the CO2 total balance value falls below a predetermined threshold value, possibly for a predetermined minimum period and by a minimum margin, the production of sponge iron in step A is stopped and the addition of stored, reduced and optionally carburized iron ore as direct reduced iron (DRI), for example in the form of HBI, is started; and, when the CO2 total balance value again exceeds the predetermined threshold value, the addition of the stored direct reduced iron is stopped and the production of sponge iron in step A is started. This approach makes it possible to control the execution of the method itself, i.e., the start and stop times of sponge iron production, depending on the current CO2 total balance value. This can achieve the advantageous effect of, for example, using DRI that happens to be inexpensively available at random times for the method, while, if the predetermined CO2 threshold requires it, the direct production of sponge iron, which may be preferable in terms of the CO2 footprint value, is preferable in order to achieve continuous compliance with the CO2 total balance value.

[0036] Preferably, the control of the addition of starting materials is by measuring the weight of the starting material added, or by measuring the volumetric flow rate of the starting material being added, or Energy flow is measured by measuring the amount of work done by the energy flow, and the CO2 footprint value and CO2 total balance value are continuously updated based on the measured values.

[0037] Regarding the CO2 total balance value, a) For crude steel from primary iron and steel production, this value must be <2050 kg CO2eq; and / or b) In the case of crude steel from secondary iron and steel products, this value must be <400 kg CO2eq; and / or c) In the case of mixtures of a) and b), the values ​​determined therefrom, for example as arithmetic mean values, are preferably adhered to.

[0038] As starting materials to be observed, for example, plastics, slag, scrap, bioresidues, filter dust, as well as residues from the paper or chemical industries can be considered. In particular, H2O, CO2, N2, CO can be considered as accompanying products.

Claims

1. A method of operating a steelmaking plant, comprising: Blast furnace / converter route The method is used The method is carried out in successive steps by supplying starting materials and by using an energy supply to obtain intermediate products, under discharge of accompanying products, and finally steel as a product, To carry out the method, A) a plurality of feed material flows of feed material; B) a plurality of entrained product flows of discharged entrained products; and C) Multiple energy flows of utilized energy Balanced and a CO footprint value is determined for each observed starting material flow, associated product flow, and energy flow; An initial CO2 footprint is determined for each starting material flow and each energy flow; For each associated product flow, a respective CO footprint connection value is determined; a CO2 total balance value is formed from the CO2 footprint values; the CO2 footprint value and the CO2 total balance value are continuously updated; when the CO2 total balance value exceeds a predetermined CO2 footprint threshold, providing the starting materials; and / or The method of claim 1, wherein the energy supply is adjusted such that the CO2 footprint value is reduced below the CO2 footprint threshold.

2. To carry out the method, A) In the blast furnace process, at least the starting materials, i.e., iron ore, coke, and air, are supplied, and in the converter process, at least the starting materials, i.e., calcium oxide and oxygen, are supplied; B) At least CO2 and slag are discharged as entrained product flows; C) Electrical energy is used to operate the equipment; determining the initial CO footprint for each starting material flow and energy flow; the initial CO footprint of the starting material is determined based on data in a database or based on values ​​provided by a supplier; the CO2 footprint connection value of the associated product flow for the associated CO2 is measured using a CO2 measurement device, preferably also by measuring the amount of at least CO and / or other carbon compounds such as CH4, or by measuring the change in the amount of emitted CO2, preferably also at least CO and / or other carbon compounds such as CH4; the calculation of the CO2 footprint connection value of the associated product flow for at least slag is carried out taking into account further use of the slag; the CO2 total balance value is determined collectively from the CO2 footprint initial value and the CO2 footprint connected value; 2. The method of claim 1, wherein, if the CO2 total balance value exceeds the predetermined threshold, the energy supply is switched to the use of renewable energy and / or starting materials of equal value with different initial CO2 footprints are stored intermediately, for example on the steel plant site, and, if the CO2 total balance value exceeds the predetermined threshold, the selection of starting materials with higher initial CO2 footprints for feeding the blast furnace / converter route is changed to the selection of starting materials with lower initial CO2 footprints for feeding the blast furnace / converter route.

3. For one or more of said starting materials, Addition of the starting material by measuring the weight of the starting material added, or by measuring the volumetric flow rate of the added starting material; or 3. The method of claim 2, wherein energy flow is measured by measuring the amount of work done by the energy flow, and the measured value is used to continuously update the CO2 footprint value and the CO2 total balance value.

4. In the blast furnace process, the starting material, i.e. i) natural gas; ii) H2, iii) Methane and further providing at least one or more of If the CO2 total balance value exceeds a predetermined CO2 footprint threshold, the proportion of natural gas and / or the proportion of H2 in the starting material flow is increased; and / or 4. The method of claim 2 or 3, wherein the proportion of H or methane from biogas production or pyrolysis of synthesis gas from recycled feedstock or biomass in the sum of the gases listed in i), ii) and iii) above is increased if the CO2 total balance value is above a second CO2 footprint threshold that is greater than the CO2 footprint threshold.

5. The blast furnace converter route includes the following measuring instruments: Measuring instruments, elemental analysis equipment (CHNS-O and / or FOES and / or ICP-OES), DCP, IR, concentration measurement, Wobbe index, GCMS, bomb calorimeter, conductivity measuring equipment, ammeter, current-voltage measuring equipment, gas volume measuring equipment, thermometer, viscosity measuring equipment, loss on ignition measuring equipment, humidity measuring equipment, C content measuring equipment for all aggregation states, 4. The method of claim 2 or 3, comprising one or more of:

6. Regarding the CO2 total balance value, a) < 2050 kg CO2eq for crude steel from primary steel products; and / or b) < 400 kg CO2eq for crude steel from secondary iron and steel products; and / or c) in the case of a mixture of a) and b), the value obtained therefrom.