Martin Niederer

Nonlinear observer for temperatures and emissivities in a strip annealing furnace

The annealing process plays an important role for the product quality of steel strips. To achieve a high product quality, an accurate temperature control is essential, which typically requires information about the temperature evolution inside the strip annealing furnace. However, usually only a few temperatures at discrete points in the furnace can be measured. Therefore, this paper proposes an extended Kalman filter and an ad-hoc adaptive estimator for the furnace temperatures. Moreover, both observers also estimate the inexactly known strip emissivity. The observers are validated by means of measurement data from an industrial furnace. This validation demonstrates the reliability and accuracy of the ad-hoc adaptive estimator.

Modeling of the media-supply of gas burners of an industrial furnace

Gas-fired industrial furnaces are used to heat products to a predefined temperature level. As the temperature of the load as well as the composition of the flue gas are crucial for many applications in industry, the controllers of burners have to ensure a given heat input and air-fuel ratio. As a basis for such controllers, an accurate mathematical model of the media supply of an industrial furnace, including valves, pressure reducing valves (PRVs), and long hot-air pipelines, will be derived from first principles and verified by means of measured data of a real plant.

Modeling of the Media Supply of Gas Burners of an Industrial Furnace

Gas-fired industrial furnaces are used to heat products to a predefined temperature level. As the temperature of the load as well as the composition of the flue gas are crucial for many applications in industry, the controllers of burners have to ensure a given heat input and air–fuel ratio. As a basis for such controllers, an accurate mathematical model of the media supply of an industrial furnace, including valves, pressure reducing valves (PRVs), and long hot-air pipelines, will be derived from first principles and verified by means of measured data of a real plant.

Modeling and control of gas supply for burners in gas-fired industrial furnaces.

In gas-fired industrial furnaces, gas burners are typically used for heating of a load. The heating process inside the furnace has a strong influence on the product quality of the load. For accurate control of the load temperature, highperformance subordinate control of the mass flow of natural gas and air to the burners is crucial. For this purpose, a mathematical model of the fuel branch of a furnace is derived based on first principles. The model is validated by means of measurement data from a real plant. Finally, a two-degrees-of-freedom control strategy based on differential flatness in combination with a simple PID-feedback controller is proposed.

Nonlinear Observer for Temperatures and Emissivities in a Strip Annealing Furnace

The annealing process plays an important role for the product quality of steel strips. To achieve a high product quality, an accurate temperature control is essential, which typically requires information about the temperature evolution inside the strip annealing furnace. However, usually only a few temperatures at discrete points in the furnace can be measured. Therefore, this paper proposes an extended Kalman filter and an ad-hoc adaptive estimator for the furnace temperatures. Moreover, both observers also estimate the inexactly known strip emissivity. The observers are validated by means of measurement data from an industrial furnace. This validation demonstrates the reliability and accuracy of the ad-hoc adaptive estimator.

Analysis of Radiative Heat Transfer in an Indirect-Fired Strip Annealing Furnace based on Integral Equations

Abstract A dynamical model of a tunnel furnace for strip annealing is proposed. The continuous furnace has a uniform cross section and is divided into several heating zones, where the local temperatures are used as model inputs. The presented model is tailored to control and optimization applications and takes into account the most important underlying physical phenomena, i.e., the energy balance of the strip and the heat transfer due to radiation. For determining the radiative heat transfer, radiation balances in the form of integral equations are used. Approximate solutions of these equations are obtained by means of the method of weighted residuals. To facilitate an accurate representation of the strip temperature, the strip motion is described based on Lagrangian coordinates, which is especially useful for capturing the temperature transition at welded joints between consecutive strips. The capabilities of the model are explored in simulation studies.