Research And Application Of Optimization Modeling For Energy-Saving And CO₂ Emission-Reduction In Iron And Steel Enterprises

Iron and steel industry which takes a decisive position in energy conservation and emission reduction works of Chinese industry is a mainstay industry of national economy meanwhile a huge energy consumer and pollutants emission source.New quota for energy consumption and CO2 emission proposed by the 13th Five-Year Plan is a challenge for iron and steel enterprises which are losing money.More investments in energy saving and emission reducing works is a disaster for iron and steel industry which is beyond a poor economic benefit.In consequence,to analyze the energy utilization of steel enterprises and control CO2 emission from the sources instead of governance is necessary and meaningful.The energy conservation and emission reduction works of Chinese iron and steel industry mainly focus on the system level instead of the process level or equipment level.Few analyses focus the enterprise level.The energy source of steel making mainly is coal and electricity.And the combination of coal and electricity is by means of material flow and energy flow network.In consequence,a 5 million ton class steel plant in China is chosen as the case plant.Under ReMIND modeling platform,the material flow and energy flow network model of case plant is built with the process integration method and steel making physical model.Steel making physical model is established to describe the relationship of input and output parameters.Material flow and energy flow network is built with the connection of upstream processes and downstream processes which including the electricity network and gas allocation.With the minimum energy consumption as the objective function,the energy consumption of case plant dropped from 670.36 kgce/t-cs to 645 kgce/t-cs,which will reduce the energy consumption by 12.68 million tee per year.With the minimum CO2 emission as the objective function,the emission of case plant dropped from 2264.66 kg CO2/t-cs to 2120.01 kg CO2/t-cs,which can reduce the emission by 72.325 million t per year.The key factor which affects the coal blending of coking process is the standard coal coefficient of coal.And the key factor which affects the blast furnace material proportioning is cost constraint.Energy saving measures can also reduce emission,but they are not equivalent.With the emission constraint,minimum energy consumption will be promoted.With the purchased scrap increase to 114.6 kg/t-cs,the minimum energy consumption and emission of case plant is 591.51 kgce/t-cs and 1965.11 kg CO2/t-cs,respectively.With all self-produced scrap recovery,production yield have little effect on energy consumption and emission.With blast furnace coal ratio raised to 200 kg/t hot metal,the minimum energy consumption dropped by 19.71 kgce/t-cs,while the minimum emission almost invariant.Blast furnace gas is the key factor for emission reducing.Equipped oxygen furnace,the minimum energy consumption and emission of case plant reduced by 36.90%and 28.41%,respectively.