Scheduling optimization problem considering time-of-use tariffs and piece-rate machine maintenance in EAF steelmaking

An operating schedule of the parallel electric arc furnaces(EAFs)considering both productivity and energy related criteria is investigated.A mathematical model is established to minimize the total completion time and the total electricity cost.This problem is proved to be an NP-hard problem,and an effective solution algorithm,longest processing time-genetic(LPT-gene)algorithm,is proposed.The impacts of varied processing energy consumption and electricity price on the optimal schedules are analyzed.The integrated influence of the different weight values and the variation between the peak price and the trough price on the optimal solution is studied.Computational experiments illustrate that considering the energy consumption costs in production has little influence on makespan;the computational performance of the proposed longest processing time-genetic algorithm is better than the genetic algorithm(GA)in the issue to be studied;considerable reductions in the energy consumption costs can be achieved by avoiding producing during high-energy price periods and reducing the machining energy consumption difference.The results can be a guidance for managers to improve productivity and to save energy costs under the time-of-use tariffs.

Simulation and analysis of O_(2)-CaO jet behavior with different shrouding fuel mediums in electric arc furnace steelmaking

The O_(2)-CaO jet with shrouding combustion flame demonstrates some advantages in quick melting and effective slag foaming by delivering lime powder deeply into the molten bath.Combining the discrete particle model and the eddy dissipation concept model with the detailed chemical kinetic mechanisms(GRI-Mech 3.0),computational fluid dynamics models of the O_(2)-CaO jet with different shrouding fuel mediums injection were developed.Firstly,the results of the numerical simulation were validated by the measured data of cold test for O_(2)-CaO injection.Then,the interaction between the particles and the gas jet of the O_(2)-CaO jet and the effect of shrouding fuel medium species on the fluid flow characteristics of the O_(2)-CaO jet were analyzed.Results show that the CaO particles can be effectively heated by the shrouding high-temperature combustion flame and compared with the O_(2)-CaO jet without shrouding gas,the potential core length was increased about 2.5,3.3 and 4.3 times by the shrouding flame generated from CO,CH_(4) and C_(3)H_(8).And with shrouding CH_(4) and C_(3)H_(8) injection,the CaO particles can be clustered together in a long distance,which would be helpful to improve the utilization efficiency of CaO particles.

A review on bath fluid flow stirring technologies in EAF steelmaking

In the contemporary electric arc furnace(EAF)steelmaking industry,increasing contents and temperature homogenization via fluid flow stirring is found to be an effective method of improving production quality and smelting efficiency.It is a trend for different factories with bowl-shaped furnaces to apply the bath fluidity enhancement technology.EAF has plenty of advantages in modern steelmaking industry,and the improvements on the EAF steelmaking process have come up with two major tasks,namely reduction in energy consumption and tap-to-tap time.The latter task requires an essential understanding of every phase in EAF steelmaking process.The flat bath phase with poor bath fluid flow was crucial to the product quality and metallurgical efficiency considering EAF’s bowl-shaped structure.The research of three stirring bath methods,oxygen jets injection,electromagnetic stirring,and bottom blowing,were introduced,and then the detailed parameters of each method with their influences on molten bath fluidity were presented.