A Fast Heuristic Algorithm for Ladle Scheduling Based on Vehicle Routing Problem with Time Windows Model

Abstract

In the process of steelmaking and continuous casting production, an optimized ladle schedule will greatly reduce energy consumption and improve production. The ladle scheduling problem can be modeled as vehicle routing problem with time windows (VRPTW) and extra constraints. The main extra constraint is that components of the ladle, at the right time, have to be repaired no later than serving certain number of heats. The objective of ladle scheduling problem is minimizing the number of serving ladles and reducing the waiting time between serving two adjacent heats. According to the serving process of ladles, a mathematical model is established to solve this specific problem. In this paper, a three-step heuristic algorithm with time complexity of O(n 2 ) is proposed, which is based on characteristics of the model and some preliminary experiments. The algorithm has been tested by several practical instances from a steel plant in China. Comparing with the schedules used in actual production, the computational results show that our algorithm optimizes the ladle schedules and solves the problem in less than 1 second, which proves the algorithm's efficiency.

Scheduling Model for the Practical Steelmaking-continuous Casting Production and Heuristic Algorithm Based on the Optimization of “Furnace-caster Matching” Mode

“…In addition, the evaluation on performance of algorithms should pay more attention to some key factors closely related to actual production, such as the consideration on the running of multiple cranes 26) and the cycling (turnover) of ladles online, 27) not just limited to the comparison on penalty values of objective functions. In this paper, the simulation model based on Plant Simulation software is applied to run the scheduling solutions solved by M 13 and A 6 with crane non-collision constraint, and further verify the availability of algorithms in practice.…”

Scheduling in Continuous Steelmaking Casting: A Systematic Review

“…A 3.31% of the publications study the scheduling of these operations in order to have the greatest possible availability of the machines. Therefore, for example, there are methodologies for planning the repair of ladles, 145) or even the contemplation of time windows for maintenance on the different machines. 49) Other studies directly involve the coordinator in the work of checking the planning in order to comply with the maintenance requirements.…”

Energy-Efficient Integration Optimization of Production Scheduling and Ladle Dispatching in Steelmaking Plants

“…It is well known that the computational complexity exponentially increases as the problem scale grows, and hence exact algorithms cannot solve the large-sized instance within an acceptable time. Heuristic algorithms focus on problemspecific features and may solve large-scale problems in extremely short computation time [24][25][26]. However, the quality of the derived solutions might not be satisfactory since it is difficult to combine all the features into a simple heuristic algorithm.…”