Patent Application
20250092477
The subject disclosure relates to a method for operating a steelworks.
Various methods for operating a steelworks for producing steel are known. The most common method at present is the so-called blast furnace converter route, i.e., the production of pig iron from iron ore using coke, now also with the partial addition of hydrogen in the form of H2 and/or CH4, in a blast furnace with subsequent further processing of the pig iron, and possibly with the addition of scrap and other additives, to produce steel. However, the blast furnace converter route has the disadvantage that it is associated with a high level of CO2 emissions.
Against the backdrop of efforts to reduce emissions of chemical compounds with an impact on the climate, alternative methods have become increasingly relevant. In the case of the operation of a steelworks, for example, the direct reduction of iron ore using hydrogen with a downstream electric steel route and oxygen steel route has become particularly relevant for avoiding CO2 emissions. Direct reduction is carried out using hydrogen as a reducing agent for the iron ore, wherein, for example, electrolytically-produced hydrogen or hydrogen bound in methane can be used.
A consideration of the emissions of gases and other materials with an impact on the climate is made possible by the well-known and practiced procedure of determining the total amount of emissions that arise directly or indirectly at various stages of a product, and taking into account the values determined as a so-called “carbon footprint.” In the case of considering CO2 as a gas with an impact on the climate, the consideration is based upon the determination of CO2 emissions that arise directly or indirectly at various stages of a product. In the case of consideration of the quantity of other gases, e.g., CO or CH4 or NOx, or other materials, e.g., particulate matter, which arise directly or indirectly in various stages of a product as gases with an impact on the climate, the consideration is based upon the determination of CO2 equivalents, which is a measure of the equivalent mass of CO2 that would be required for an equivalent average warming effect of the Earth's atmosphere over a certain period of time—for example, 100 years. Tracing emissions of gases or other materials with an impact on the climate back to CO2 equivalents has the advantage that different emissions can be easily compared.
Against the background of efforts to reduce the emission of gases with an impact on the climate in steel production and at the same time maintain good economic efficiency in steel production, it is preferred to ensure a comprehensive view of the production process.
One object of the subject disclosure is to ensure or at least facilitate such a comprehensive view.
According to one aspect, this object is achieved by a method for operating a steelworks with the features of claim 1.
The following in particular can be used:
The method can be carried out by supplying starting materials and using energy. During the method, intermediate products are formed in a number of consecutive method steps and with the emission of accompanying products, and, finally, steel is obtained as a product.
According one aspect, it is provided that at least the following material flows be balanced in order to carry out the method:
In order to accomplish such balancing, a CO2 footprint value is determined for each starting material flow, each accompanying product material flow, and each energy flow under consideration.
To distinguish between the different CO2 footprint values formed, a CO2 footprint initial value is determined for each starting material flow and for each energy flow, and a CO2 footprint connection value is determined for each accompanying product material flow. A total CO2 balance value is calculated from the aggregate of the CO2 footprint values. While the method is carried out, the CO2 footprint values and the total CO2 balance value are continuously updated.
The term, “CO2 footprint value,” covers both the emission of CO2 and the emission of other gases and other materials with an impact on the climate as CO2 equivalents. The same applies to the CO2 footprint initial value, the CO2 footprint connection value, and the CO2 footprint value, which always refer not only to CO2 itself, but also to the CO2 equivalents of other gases and materials with an impact on the climate.
The balancing of CO2 footprint values means in particular that, for each starting material, each accompanying material, and the energy used to operate the plants, the entire material flow from the source up to the use, and preferably up to the end of life, is considered, and this is given a CO2 footprint value. The term, “CO2 footprint value,” means that the total amount of CO2 or a CO2-equivalent observation value that is linked to the material flow is balanced relative to a reference value for the respective material flow. For example, the total amount of CO2 and the total amount of CO2 equivalent in kilograms emitted during the production of 1 t of end product, e.g., hot-rolled steel, can be recorded for each material flow, wherein all production and other treatment steps, including transportation and the like, are taken into account. The balancing can be implemented step-by-step by providing a one-dimensional or multi-dimensional list, in which each material flow under consideration, and preferably each existing material flow, is contained and in which each material flow under consideration, and preferably each existing material flow, is assigned a CO2 footprint value. The total CO2 balance value is calculated using the CO2 footprint values and assigns only one total CO2 balance value to the production of the end product—for example, 1 t of end product. This is a measure of the amount of CO2 emitted during the production of the end product. It is essential that the total CO2 balance value be based upon an aggregate of CO2 footprint values that are taken into account for each starting material flow, accompanying product material flow, and energy flow under consideration and, preferably, be continuously updated. Through this procedure, it can be ensured in particular that the CO2 emissions that take place in connected and upstream value chains can also be taken into account when calculating the total CO2 balance value. In particular, possible CO2 emissions can also be taken into account, such that, for example, binding CO2 as part of the overall process has a positive effect on the total CO2 balance value.
According to one aspect, it is provided that, if the total CO2 balance
In other words, the total CO2 balance value is compared continuously or quasi-continuously, i.e., in a recurring sequence, with a CO2 footprint threshold value, and, in the event that such threshold value is exceeded, the procedure for carrying out the method for operating a steelworks is adjusted. The adjustment is made in the supply of starting materials, the supply of energy, or both. The adjustment can be made, for example, in such a way that a sub-selection or a specific composition of the selection is made from a predetermined selection of starting materials, for each of which material-specific CO2 footprint values are stored, as a function of the amount of the total CO2 balance value. The adjustment can alternatively or additionally be effected step-by-step in such a way that the energy supply is changed to the extent that the selection of power supply is selected as a function of electricity production.
In a first method variant, the blast furnace converter route is used.
To carry out the method,
Based upon such an initial setup, a CO2 footprint initial value is determined for each starting material flow and for each energy flow. A starting point for determining the CO2 footprint initial values of the starting materials is found, for example, on the basis of database data or on the basis of CO2 footprint values provided by the supplier, or chemical analyses carried out by the company itself.
For determining the CO2 footprint connection value of the accompanying product material flow, which is specific for each accompanying material, for the accompanying material of CO2, a measurement of the amount of CO2 emitted, and preferably also other carbon compounds such as at least CO and/or CH4, is carried out, or a measurement of a change in the amount of CO2 emitted, and preferably also other carbon compounds such as at least CO and/or CH4, is carried out, wherein one or more CO2 measuring devices arranged at suitable locations in the steelworks, and, optionally, additionally a C measuring device, are used for the measurement. The measuring devices are preferably used for measuring in the solid and/or liquid and/or gaseous aggregate states. Thus, a direct measurement is used to determine how much CO2, and preferably also other carbon compounds such as at least CO and/or CH4, is emitted in the steelworks during its operation. The specified CO2 footprint connection value is determined from the measured value(s) obtained.
For the accompanying material of slag, a calculation of the CO2 footprint connection value of the accompanying product material flow is carried out, taking into account the further use of the slag. This can include, for example, balancing the use of the slag as a road surface by comparing the alternative use of another material as a road surface which may have a higher CO2 footprint value, wherein, in this example, the CO2 footprint connection value for the accompanying material flow of the slag can also be negative.
Preferably, other accompanying materials are also considered: For one or more of the accompanying materials of tar, sulfur, benzene, heat, or steam, the CO2 footprint connection value of the accompanying product material flow is calculated, taking into account the further use of the accompanying material or materials.
In this example, the total CO2 balance value is determined, for example, summarily from the CO2 footprint initial values and the CO2 footprint connection values.
In the described further development, in a case where the total CO2 balance value exceeds the predetermined threshold, the energy supply can, for example, be switched to the use of available energy generated from wind turbines, and/or equivalent starting materials with higher CO2 footprint initial values can be temporarily stored, e.g., on the steelworks site, and, if the total CO2 balance value exceeds the predetermined threshold, a selection of a starting material with a higher CO2 footprint initial value for supply to the blast furnace converter route is changed to a selection of a starting material with a lower CO2 footprint initial value for supply to the blast furnace converter route. In this way, for example, the monitoring of the CO2 footprint value in real time or close to real time can be used to control the operation of the steel mill across all process chains in such a way that its total CO2 balance value remains permanently below the predetermined threshold, with the advantage that a contribution can be made to achieving the long-term goal of climate neutrality. The steelworks operation is therefore controlled, and preferably optimized, based upon the overall consideration of the CO2 footprint values of all the starting material flows, accompanying product material flows, and energy flows under consideration, forming a total CO2 balance value.
Preferably, the control of the starting materials is carried out by means of measuring the weight of the added starting material, or by means of measuring a volume flow of the added starting material, or, for an energy flow, by means of measuring a working quantity of the energy flow, wherein the CO2 footprint values and the total CO2 balance value are continuously updated based upon the measured values.
Preferably, one or more of the following specified starting materials is also supplied in the blast furnace method step:
In particular, it can be provided that the blast furnace converter route have one or more of the following specified measuring devices:
In a second method variant, the direct reduction of iron ore with hydrogen is used with a downstream electric steel route.
To carry out the method,
Similarly to the procedure explained in connection with the blast furnace converter route, the CO2 footprint initial values of the starting materials are determined on the basis of database data or values provided by the supplier.
The CO2 footprint connection value of the accompanying product material flow for the accompanying material of CO2 is measured by means of a CO2 measuring device by means of measuring the amount of CO2 emitted or measuring a change in the amount of CO2 emitted. Preferably, the CO2 footprint connection value of the accompanying product material flow for the accompanying materials of CO and CH4 is measured by means of a C measuring device by means of measuring the amount of C emitted or measuring a change in the amount of C emitted.
The total CO2 balance value is determined, for example, summarily from the CO2 footprint initial values and the CO2 footprint connection values.
In a similar way to that described above in connection with the blast furnace converter route, if the total CO2 balance value exceeds a predetermined threshold, the energy supply is switched to the use of low-carbon energy—for example, renewably produced energy or nuclear power.
Alternatively or additionally, equivalent starting materials with different CO2 footprint initial values are temporarily stored, e.g., on the steelworks site, and, if the total CO2 balance value exceeds the predetermined threshold, the selection of a starting material with a higher CO2 footprint initial value for supply to the direct reduction plant or at another input point of the production route is changed to a selection of a starting material with a lower CO2 footprint initial value for supply to the production route. This means that, by storing starting materials with different CO2 footprint initial values when considering the entire value chain, it is ensured that starting materials produced while avoiding CO2 are kept ready in order to use them, if necessary, to reduce the total CO2 balance value below a predetermined threshold to be able to select for supply to the method. This procedure is an advantageous way of ensuring that a total CO2 balance value can be kept permanently below a predetermined threshold.
Alternatively or additionally, it is possible to proceed in such a way that, if the total CO2 balance value falls below the predetermined threshold by a minimum margin—if necessary, for a predetermined minimum period of time—the production of sponge iron is stopped in step A, and the addition of temporarily stored, reduced, and optionally carburized iron ore, e.g., as direct reduced iron (DRI) in the form of HBI, is started, and, if the total CO2 balance value exceeds the predetermined threshold again, the addition of temporarily stored direct reduced iron is stopped, and the production of sponge iron is started in step A. This procedure allows the method control itself, i.e., the start time of sponge iron production and the stop time of sponge iron production, to be controlled depending upon the current total CO2 balance value. This can, for example, achieve the advantageous effect that DRI that can be procured inexpensively at random times can occasionally be used for the described method, but, 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 preferred in order to ensure continuous compliance with the total CO2 balance values.
Preferably, the control of the starting materials is carried out by means of measuring the weight of the added starting material, or by means of measuring a volume flow of the added starting material, or, for an energy flow, by means of measuring a working quantity of the energy flow, wherein the CO2 footprint values and the total CO2 balance value are continuously updated based upon the measured values.
For the total CO2 balance value, it preferably applies
The starting materials considered can include plastics, slag, scrap, biogenic residues, filter dust, and residues from the paper industry or the chemical industry. In particular, H2O, CO2, N2, CO can be considered as accompanying product materials.
| Number | Date | Country | Kind |
|---|---|---|---|
| DE102021125784.0 | Oct 2021 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/071809 | 8/3/2022 | WO |
