In today`s steel industry about one third of the total steel production is produced by electric arc steel making. The production of steel is a very energy intensive industry, but when considering the total cost of the final steel mill product, it is the cost of raw materials that are dominating. A global trend for the manufacturing industry isto produce more energy effective products by usinglow alloyed steels which in turn affects the scrap based steel industry. Thereforean increased need of iron ore based metallic, such as direct reduced iron (DRI)and hot briquetted iron (HBI), as scrap supplement is then needed formaintaining low levels of trace elements in the produced steel. The selection ofraw materials is a matter that affects the conditions for the entire productionsystem, product properties, slag properties, off gas and dust generation, energyuse and the conditions for processes downstream.For the integrated iron and steel industry and also for other energy intensiveprocess industry, research in the field of process integration has shown goodresults regarding optimization of energy use and material utilization. Theapplication of process integration as a method for the scrap based industry, andin particular for Höganäs AB:s production system, is discussed in the thesis.Mixed Integer Linear Programing has been used to develop system models foroptimization and evaluation of costs and energy usage. Also processes notpresent in Höganäs current production system have been developed for analysisof future raw material scenarios. The current system models include six mainprocess steps: a direct reduction process, an electric arc furnace, a ladle furnace, a continuous casting process and a hot rolling mill. Among the presented results in this thesis, a major result is the models` ability to predict and constrain product quality in an improved way and show potentialcost- and energy savings for the modeled production system. Furthermore,another very useful result is the models` ability to minimize cost and energy usefor sequences of different product qualities, while taking stock levels intoconsideration. A constant concern for steelmakers is that raw material prices, composition and availability are changing and fluctuating over time. Therefore, system modeling can be seen as a good tool for helping to maintain flexibility in production units by taking advantage of these market fluctuations to keep conversion costs andenergy use at lowest levels possible
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:ltu-18038 |
| Date | January 2014 |
| Creators | Lingebrant, Philip |
| Publisher | Luleå tekniska universitet, Energivetenskap |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Licentiate thesis, comprehensive summary, info:eu-repo/semantics/masterThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | Licentiate thesis / Luleå University of Technology, 1402-1757 |
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