Optimization and continuous casting: Part I. Problem formulation and solution strategy
| Autor: | Lorenz T. Biegler, B. Lally, Hani Henein |
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| Rok vydání: | 1991 |
| Předmět: | |
| Zdroj: | Metallurgical Transactions B. 22:641-648 |
| ISSN: | 2379-0229 0360-2141 |
| DOI: | 10.1007/bf02679019 |
| Popis: | Optimization strategies determine process parameters that maximize or minimize some aspect of a process (the objective), while ensuring that the process operates within established limits or constraints. The optimization problem is formulated as a constrained, nonlinear programing (NLP) problem, is solved using successive quadratic programing (SQP), and is applied to the continuous casting of steel. The process status and constraints are evaluated with the aid of a heat flow and solidification model. In this study, we also present the casting objectives of maximum casting rate and formulate the casting constraints. These constraints can represent product quality and process feasibility through limits on strand shell thickness, metallurgical length, maximum heating and cooling rate, casting rate, and reheating of the strand surface. The constraints formulated are representative of a range of typical caster mechanical, thermal, and solidification constraints. To illustrate the capabilities of the method, a small casting example previously reported in the literature is solved using SQP. It is shown that considerable attention must be paid to the formulation in order to derive smooth objective and constraint functions for SQP. An important advantage of this solution technique is that the formulation contains casting rate and spray cooling parameters and that the solution satisfies all constraints. The results are achieved in a single solution to the nonlinear constrained optimization problem. The solution of more complex caster optimization problems is reported in Part II.[22] |
| Databáze: | OpenAIRE |
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