Coil batching to improve productivity and energy utilization in steel production

This paper investigates a practical batching decision problem that arises in the batch annealing operations in the cold rolling stage of steel production faced by most large iron and steel companies in the world. The problem is to select steel coils from a set of waiting coils to form batches to be annealed in available batch annealing furnaces and choose a median coil for each furnace. The objective is to maximize the total reward of the selected coils less the total coil'coil and coil'furnace mismatching cost. For a special case of the problem that arises frequently in practical settings where the coils are all similar and there is only one type of furnace available, we develop a polynomial-time dynamic programming algorithm to obtain an optimal solution. For the general case of the problem, which is strongly NP-hard, an exact branch-and-price-and-cut solution algorithm is developed using a column and row generation framework. A variable reduction strategy is also proposed to accelerate the algorithm. The algorithm is capable of solving medium-size instances to optimality within a reasonable computation time. In addition, a tabu search heuristic is proposed for solving larger instances. Three simple search neighborhoods, as well as a sophisticated variable-depth neighborhood, are developed. This heuristic can generate near-optimal solutions for large instances within a short computation time. Using both randomly generated and real-world production data sets, we show that our algorithms are superior to the typical rule-based planning approach used by many steel plants. A decision support system that embeds our algorithms was developed and implemented at Baosteel to replace their rule-based planning method. The use of the system brings significant benefits to Baosteel, including an annual net profit increase of at least 1.76 million U.S. dollars and a large reduction of standard coal consumption and carbon dioxide emissions

Preliminary Evaluation for Lean Implementation in a Small Manufacturing Company

Lean management and tools have many positive effects on a company including increased profitability, and efficiency. Lean tools can be implemented in any type of company with a proper evaluation through the creation of Value Stream Map. This paper will demonstrate how a Value Stream Map (VSM) will provide an easier transition to a lean environment. A local company of about 100 employees will be analyzed to create a current and a future VSM. The areas of opportunity for improvement in a lean environment includes recommended lean implementations and the future VSM. Functions of the company that will be analyzed regarding the implementation of VSM include: shipping, receiving, and operations. This project will demonstrate the gap between the current state VSM and the future VSM

Throughput and Yield Improvement for a Continuous Discrete-Product Manufacturing System

A seam-welded steel pipe manufacturing process has mainly four distinct major design and/or operational problems dealing with buffer inventory, cutting tools, pipe sizing and inspection-rework facility. The general objective of this research is to optimally solve these four important problems to improve the throughput and yield of the system at a minimum cost. The first problem of this research finds the optimal buffer capacity of steel strip coils to minimize the maintenance and downtime related costs. The total cost function for this coil feeding system is formulated as a constrained non-linear programming (NLP) problem which is solved with a search algorithm. The second problem aims at finding the optimal tool magazine reload timing, magazine size and the order quantity for the cutting tools. This tool magazine system is formulated as a mixed-integer NLP problem which is solved for minimizing the total cost. The third problem deals with different type of manufacturing defects. The profit function of this problem forms a binary integer NLP problem which involves multiple integrals with several exponential and discrete functions. An exhaustive search method is employed to find the optimum strategy for dealing with the defects and pipe sizing. The fourth problem pertains to the number of servers and floor space allocations for the off-line inspection-rework facility. The total cost function forms an integer NLP structure, which is minimized with a customized search algorithm. In order to judge the impact of the above-mentioned problems, an overall equipment effectiveness (OEE) measure, coined as monetary loss based regression (MLBR) method, is also developed as the fifth problem to assess the performance of the entire manufacturing system. Finally, a numerical simulation of the entire process is conducted to illustrate the applications of the optimum parameters setting and to evaluate the overall effectiveness of the simulated system. The successful improvement of the simulated system supports this research to be implemented in a real manufacturing setup. Different pathways shown here for improving the throughput and yield of industrial systems reflect not only to the improvement of methodologies and techniques but also to the advancement of new technology and national economy

Evaluating Identification and Sorting Technologies for Improved Ferrous and Non-Ferrous Recycling

Metals recycling is one of the oldest industries in the United States that now employs over 530,000 individuals. It has always played a significant role in the economy, contributing $109.78 billion to the US economy in 2018. Furthermore, recycling supplies extensive goods and services, the Institute of Scrap Recycling Industries (ISRI) reported that every year greater than 900M Mt of scrap (~2 billion pounds) are consumed by manufactures globally, equating to 40% of the raw material demand. Additionally, as climate change becomes a greater threat, we must seek practices to lessen our carbon footprint, and recycling helps to reduce the environmental impact of metal production. Relying on this industry as an alternative to make-take-waste habits means understanding how the industry’s efficiency is being challenged by growing feed volumes of diverse, complex product designs. This work details the internal and external factors that impact the development of ferrous and nonferrous recycling operations. This knowledge is then applied to design and perform an extensive “true to yard” analysis with technologies that have potential for addressing inbound inspection and material identification challenges. These results allowed us to understand the limitations that would arise when attempting their deployment at material handling facilities, and then use these factors to build a model capable of quantifying and comparing these techniques, which is not available in previous literature. Inbound inspection and material identification are critical; they are the first opportunity once material is received to prevent comingling, downcycling, and contamination. Scrap yards identify and sort specific alloys from large quantities of mixed metals by means of visual and cognitive recognition with the aid of a few standard tools (a magnet, file, acids, and/or grinding wheel). This work tested handheld analyzers (HHs) that utilize x-ray fluorescence (XRF) and laser induced breakdown spectroscopy (LIBS) technology to determine the level of technological assistance they can provide to improving identification during the inspection process. Beforehand, we had a good indication of how HHs perform on material that has clean, smooth, uncoated surfaces (prompt scrap) but, what we aim to find is their response when used on “unprepared materials,” like those coming out of stock that are old, used, weathered, and/or warped (obsolete scrap). For these instruments to be deemed useful for inbound inspection/ identification purposes, it is crucial to understand and evaluate their limitations on scrap that is not altered and thus, true to a yard setting. Results indicate that in their current state, HHs can inform and verify content for a significant range of materials. They also show grade matching (identification of an alloy by name) is possible but less likely on unprepared scrap. However, the ability to register and share elemental composition percentages at rapid speeds, allows a trained user to know immediately what contaminants are present, often being high levels of Si and Fe. In addition to understanding how these technologies perform under real world conditions, it is also important to quantify whether their benefits outweigh their costs. This work examined five different scenarios for sorting and identification, each scenario offering different levels of alloy-specific sorting capabilities. The model that was created allowed for return on investment (ROI) comparisons, and evaluated the impacts of different market conditions, changes in volume, volume distribution, and uncertainty. This technoeconomic assessment showed that even a high amount of comingled material can be profitable at high volumes under certain market conditions. Although, comingling led to diminished profits, where segregating proved beneficial even at lower volumes. As we continue to invest, educate, and execute sustainable practices, we must understand that recycling should only come as an attempt after we have exhausted our efforts to reduce and reuse. Moreover, we can work to obtain a better balance along the supply chain by encouraging and creating more practices like design for recycling (DfR) and extended producer responsibility. Being that these behaviors will require a lot of societal reform, we need to ensure that we work to reduce landfill feed by providing the recycling industry with the tools and practices that are effective and efficient at getting materials identified and sorted

Numerical investigation of the use of externally generated Lorentz forces to improve the flow pattern in a continuous glass-melting tank

Das elektromagnetische Boosting (EMB) ist ein neuer und innovativer Lösungsansatz zur Verbesserung der Strömungsverhältnisse in den kontinuierlich arbeitenden Glasschmelzwannen mit einer elektrischen Zusatzbeheizung. Das EMB basiert auf der Benutzung von extern induzierten Lorentzkräften, die entgegen der Hauptströmungsrichtung in der Schmelzwanne gerichtet sind. Die Generierung dieser zusätzlichen Lorentzkräfte erfolgt durch die Überlagerung eines externen Magnetfeldes mit der in der Glasschmelze fließenden elektrischen Ströme. Das externe Magnetfeld wird von zusätzlichen Magnetspulen generiert. Diese werden unterhalb des Wannenbodens zwischen den Elektroden der Zusatzbeheizung installiert. Dadurch wird ein steuerbarer elektromagnetischer Wall in der Glasschmelze zwischen den Elektroden realisiert. Dieser verhindert die unerwünschte Strömung der kälteren, bodennahen Glasschmelze zum Wannenauslass. Als Ergebnis wird die minimale Verweilzeit (MRT) der Glasschmelze in der Wanne erhöht und somit die Verweilzeitverteilung (RTD) verbessert. Als Ergebnis wird die Glasqualität erhöht. In dieser Dissertation wird das EMB in einer Glasschmelzwanne numerisch untersucht und somit die Grundlage für eine industrielle Anwendung gelegt. Die stark temperaturabhängigen Materialeigenschaften von Glas erfordern gekoppelte Berechnungen von Elektro-, Thermo- und Hydrodynamik, die zu hochkomplexen, dreidimensionalen, numerischen Simulationen der Problemstellung führen. Die Simulationen werden für eine reale industrielle Glasschmelzwanne unter Annahme einiger Vereinfachungen durchgeführt. Die Randbedingungen sind so definiert, dass die realen Betriebsverhältnisse der Wanne simuliert werden können. Für das EMB wird ein zusätzliches Spulensystem angepasst. Die Simulationen zeigen, dass es im Prinzip möglich ist, einen steuerbaren elektromagnetischen Wall im Boostingbereich zu erzeugen. Um die optimale Wirkung des EMB zu erzielen, sind Parameterstudien durchgeführt worden. Mit diesen Simulationen wird erstmals das dynamische Betriebsverhalten einer Glasschmelzwanne mit EMB untersucht. Die Ergebnisse zeigen, dass die gewünschte wesentliche Erhöhung von MRT und die damit verbundene Verbesserung von RTD mit Hilfe des EMB erzielbar sind, wodurch die Qualität des Endproduktes erhöht wird. Des Weiteren kann mit Hilfe des EMB die Glasqualität verbessert und gleichzeitig der Durchsatz der Wanne erhöht werden. Unter normalen Betriebsverhältnissen ohne das EMB ist dies nicht möglich. Diese theoretischen Untersuchungen bilden den ersten Schritt, das EMB in der Praxis zu testen und einzusetzen, um neuartige Glasschmelzwannen mit höherem Wirkungsgrad und verbesserter Qualität des Glasproduktes in der Industrie einzuführen.Electromagnetic boosting (EMB) is a new and innovative approach for improving the flow patterns within electrically boosted continuous glass-melting tanks. EMB is basically achieved by electromagnetic (Lorentz) forces that are orientated against the main flow direction of the glass melt in the tank. The additional Lorentz forces are produced within the glass melt by an externally generated magnetic field interacting with the electric currents that exist within the glass melt. For the process, additional magnet coils are placed underneath the tank bottom and positioned between heating electrodes. Thus, a controllable electromagnetic wall is created in the boosting area to impede the flow of the colder, less well-melted bottom glass through the gaps between the electrodes towards the tank-outlet. The desired EMB effect is an increase in the minimum residence time (MRT) of the glass melt within the tank and consequent improving of the residence time distribution (RTD), with enhanced glass quality as the ultimate result. Using numerical tools, the author of this thesis has realized and evaluated the EMB in a continuous glass-melting tank, laying the foundation necessary for the idea to be converted into an effective industrial process. As the physical properties of glass are strongly temperature-dependent, the numerical simulation involves calculation of the coupled electrodynamic, thermodynamic, and hydrodynamic effects. The investigation thus largely consists in a highly complex coupled three-dimensional mathematical problem. The simulations are performed for a particular industrial-scale continuous glass-melting tank which is represented in academic form. The boundary conditions are so defined as to simulate the realistic conditions of the particular tank. An external magnet coils system which would produce EMB in the particular tank is incorporated into the calculations. The simulations show that it is basically possible to create an electromagnetic wall within the glass melt between the heating electrodes. Parameter analyses for optimization of the EMB effect are also presented. The simulation results make it possible, for the first time, to analyze the dynamic behavior of an electromagnetically boosted continuous glass-melting tank in operation. They also reveal that EMB affects the glass melt flow within the tank favorably, increasing the MRT substantially and thus enhancing the glass quality. Moreover, the tank simulations with EMB show that it is possible to increase the tank productivity and enhance the glass quality simultaneously, which is not possible in the ordinary tank operation case without EMB. Through the author’s work, the first step, always the most important, has been taken en route to a sophisticated glass-melting tank characterized by high efficiency and high production quality

Methodology for the design of precast concrete plants.

Massachusetts Institute of Technology, Dept. of Civil Engineering. Thesis. 1972. M.S.MICROFICHE COPY ALSO AVAILABLE IN BARKER ENGINEERING LIBRARY.Bibliography: leaves 333-343.M.S

Inventory control strategies for steel industry supply chain.

Abstract not provided