Supervisory-plus-regulatory control design for efficient operation of industrial furnaces

A two-level system engineering design approach to integrated control and supervision of industrial multi-zone furnaces has been elaborated and tested. The application case study is the three-zone 25 MW RZS furnace plant at Skopje Steelworks. The integrated control and supervision design is based on combined use of general predictive control optimization of set-points and steady-state decoupling,at the upper level, and classical two-term laws with stady-state decouling, at the executive control level. This design technique exploits the intrinsic stability of thermal processes and makes use of constrained optimization, standard non-parametric time-domain process models, identified under operating conditions, using truncated k-time sequence matrices, controlled autoregressive moving average models. Digital implementations are sought within standard computer process control platform for practical engineering and maintenance reasons

Plate rolling mill flow development

Abstract. The purpose of the work was to define problem areas in terms of the flow of plate production that are within the scope of production planning during the times of low slab level. In order to achieve this goal, the aim was to study the different stages of plate production. Taking into account the production planning operations and the production itself from the steel plant to the plate rolling mill was an essential topic. Numerous personal interviews, interpretation of production data and illustrating information and material flows were the basis of the empirical work. The work sought to identify problems and produce relevant additional information to support the production planning. Lean tools were used to identify the problems and the visual illustrations were made with Microsoft Excel and the diagram drawing software Draw.io. One conclusion is that during the times of low slab level, the importance of prioritizing the right production is emphasized. Production planning’s ability to contribute to production flow can be enhanced. The ability to plan and prioritize strands whose contents in terms of cutting routes best balances each other. Strands planned in this way are in a better position to create a rolling cycle that causes less congestion. The most significant improvement suggestions are add-ons for the planning software, which help production planning to prioritize the right strands and a new operating model for the sequence planning. The working methods are generally applicable to production lines and processes. The results themselves consist of the output from this particular point in time and the specific situation in the production chain; therefore, they are not applicable for general use.Levyvalssaamon virtauksen parantaminen. Tiivistelmä. Työn tarkoituksena oli määritellä matalaan aihiovarastotasoon liittyviä tuotannonsuunnittelun vaikutuspiirissä olevia levytuotannon virtausta rajoittavia ongelma-alueita. Tämän tavoitteen saavuttamiseksi oli tutkittava laajasti levytuotannon eri vaiheita. Keskeisenä aiheena oli tuotannon suunnittelutoimintojen ja itse tuotannon kattava tutkiminen ja mallintaminen. Työn empiirisen osion perustana olivat lukuisat henkilöhaastattelut, tuotantodatan tulkinta sekä informaatio- ja materiaalivirtojen havainnollistaminen. Työssä myös pyrittiin nostamaan tuotannonsuunnittelun kykyä tunnistaa havaittuja ongelmia varhaisemmassa vaiheessa. Ongelmien tunnistamiseen käytettiin Lean-työkaluja. Visuaaliset havainnollistukset tehtiin Microsoft Excel ohjelmalla ja Draw.io kaavionpiirustusohjelmalla. Levyvalssaamon virtauksen kannalta oleellista kyky suunnitella ja priorisoida sellaisia sulatuksia, joiden sisältöjen leikkaustapakohtaiset osuudet tasapainottavat parhaiten toisiaan. Sillä tavalla suunnitelluista ja priorisoiduista sulatuksista on nykyistä paremmat edellytykset luoda sellaista valssausjaksoa, joka aiheuttaa nykyistä vähemmän ruuhkaa. Yhdeksi johtopäätelmäksi saatiin, että oikean tuotannon ja tekemisen merkitys korostuu matalan aihiovarastotason aikana. Tuotannonsuunnittelun kykyä myötävaikuttaa virtaukseen voidaan nostaa. Merkittävimpiä kehitysehdotuksia ovat sulatuksien priorisointia helpottavien suunnitteluohjelmistojen lisäosat ja uuden toimintamallin luonti valssausjakson suunnitteluun. Työssä käytetyt tutkimusmenetelmät soveltuvat yleisesti tuotantolinjoille ja prosesseille. Tulokset itsessään ovat tuotos tietyn ajankohdan ja tuotantoketjun tilanteesta eivätkä siksi sovellu yleiseen käyttöön

Nucor Corporation: A Study on Evolution Toward Strategic Fit

For much of its century long history, Nucor Corporation and its predecessors displayed turbulent financial performance. Several attempts at a strategic realignment proved unsuccessful, and in 1965, the company faced insolvency. Since that time, however, the company has rallied around its steel operations to become the largest steel producer in the United States, with $12.7 billion in net annual sales. This thesis examines Nucor’s development from an unprofitable conglomerate to a highly efficient enterprise. Specific focus on the evolution of the activity system underlying the organization lays the groundwork for systematic analysis of why some companies succeed while others fail

A study of the thermal dynamics of the reheat furnace

Reheat furnaces are for heating slabs to the best temperature distribution in the shortest time and to do this with the highest thermal efficiency. But these two performance indices are difficult to control and have not been successfully controlled so far. With the advent of on-line digital computer systems this has become possible. A comprehensive study of the thermal dynamics of the reheat furnace is carried out in this thesis with the aim of developing a control system based on computers for these two performance indices

Views on the Subject of Multilevel Control

The title of my talk suggests that my remarks be more philosophical than technical, more general and broad brush than detailed and specialized. I will, nevertheless, take the liberty of somewhat limiting the scope in order to focus very specifically on some problems related to the application of multilevel concepts and techniques to control of complex industrial systems. In the control of industrial systems, we consider the overall goal to be, in a very general sense, the efficient utilization of resources (e.g. material, energy, environmental, labor, capital) in the production of products satisfying quality specifications and consistent with goals and constraints which may be imposed by society. Thus, we are concerned with the broad spectrum of decision-making and control functions (e.g. process control, operations control, scheduling, planning, etc.) which play a role in the effective operation of the system with respect to its production goals. The control problem in this generalized context is extremely difficult to handle; we formulate various multilevel/multilayer, hierarchical structures to provide rational and systematic procedures for resolving the problem