Abstract: A method and device for controlling a melting and refining process in an electric arc furnace for melting a metal, wherein the electric arc furnace includes molten and solid metal and a slag layer on the surface of the molten metal, wherein an electromagnetic stirrer is arranged for stirring the molten metal. The method includes calculating/determining masses of the molten and solid metal at a point of time, wherein the calculation is based on initial values of the molten and solid metal, an arc power supplied to the electric arc furnace, and temperatures of the molten and solid metal, determining a stirring power based on the calculated/determined masses, and supplying the determined stirring power to the electromagnetic stirrer.

Abstract: A method of controlling a melting process in an electric arc furnace for melting a metallic material. By means of the present disclosure it is possible to minimize desired process properties such as the melting time or the total power consumption of the melting process. The method includes the steps of receiving or collecting measured data of at least one process variable, determining the current state of the process, performing an optimization of the melting process, determining a process input based on the result of the optimization, and controlling the melting process by means of the process input. A control system is also presented herein.

Abstract: A method of controlling fluid flow in a fluid network system by means of a plurality of fluid machines. The disclosure provides a simple empirical method of identifying network characteristics of the fluid network system used for providing the required fluid flow rate in the fluid network system utilizing minimal fluid machine power. The method includes the steps of determining a relation between a change in fluid machine speed and a corresponding change in fluid flow rate for each of the plurality of fluid machines empirically; determining a minimum total fluid machine power which provides a minimum required flow rate in the fluid network system based on a constraint involving the relation between the fluid flow rate and the corresponding fluid machine speed, and controlling a speed of the plurality of fluid machines such that the minimum total fluid machine power in the fluid network system is attained.

Abstract: A computer based method of controlling an industrial process, including the steps of measuring the values of at least one process variable (y1, y2), and predicting future deviations of one process variable (y1) with regard to the measured value of said at least one process variable (y1, y2), and providing a control signal (uFB) based on said predictions, and by means of a first control law. The method comprises the further steps of measuring a measurable disturbance (d) in the process, predicting future deviations of said process variable (y1) with regard to said disturbance but without regard to the measured value of said at least one process variable (y1, y2), and providing a control signal (ud) based on said predictions by means of a second control law.