(374e) Optimal Distribution of Byproduct Gases, Steam and Power in an Iron and Steel Plant
Byproduct gases, steam and electricity play an important role in providing energy for production units in the iron and steel industry. Optimal distribution of byproduct gases, steam and electricity in an iron and steel plant can significantly decrease energy cost and reduce CO2 emissions. However, such optimal distribution is not trivial because it involves many production units, steam turbines, combined heat and power units, and waste heat and energy recovery units, and several realistic operational features such as byproduct gas mixing, gasholder level control, minimum heating and energy requirement, and maximum allowable burner switches, resulting in a large complex combinatorial problem. In this presentation, we develop a novel multi-period mathematical model for optimal distribution of byproduct gases, steam, and power in an iron and steel plant. The consuming rates of byproduct gases are variable. Different byproduct gases are allowed to be mixed in order to satisfy minimum heating and energy requirement of production units. Electricity purchase and sale decisions with each having different price are correctly modelled with new binary variables. The burner switching operation is correctly modelled with fewer binary variables allowing turning on and off at any time. Several important practical features such as fuel selection, gasholder level control, ramp rate variation, piecewise constant generation rates of byproduct gases, and piecewise constant demand profiles of byproduct gases, steam and electricity are also incorporated. The computational results demonstrate that the optimal operating cost is obtained within 2 CPU seconds for an industrial example using the proposed model, which is reduced by 6.25% compared to that from actual operation.