Mathematical model for diagnosis of energy consumption bottlenecks in steel plants and its application

In order to solve the problem that material flows and energy flows both have influences on energy consumption in steel plants,a diagnosis model of energy consumption bottlenecks was established.The model uses steel ratio and process energy consumption to measure the material flows and energy flows,respectively.The function of the model is to decompose the change in energy consumption per ton steel into the changes in steel ratio and process energy consumption,so that the two factors effects can be separated, and thus the energy consumption bottlenecks can be found. The model analysis was done through three steps, correspondingly aiming at the main-process stream, the district and the process. Meanwhile, a new concept of contribution index was defined, which can indicate the effects of every factor on the energy consumption per ton steel. The model was applied to analyze the energy consumption indexes of a typical iron and steel enterprise in China using the data of energy consumption in 2001 and 2007, and the energy consumption bottlenecks in the steelmaking process were analyzed. The result shows that the restraining factors of energy consumption are the steel ratio of iron making district and steel rolling district and the process energy consumption of steel making district. At last, energy-saving measures, such as increasing the ratio of hot load and hot transportation and cutting down the fuel consumption of heating furnaces, were proposed.