Annealing Furnace

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Andreas Kugi - One of the best experts on this subject based on the ideXlab platform.

  • Nonlinear model predictive control of the strip temperature in an Annealing Furnace
    Journal of Process Control, 2016
    Co-Authors: Martin Niederer, Stephan Strommer, Andreas Steinboeck, Andreas Kugi
    Abstract:

    Abstract A nonlinear model predictive controller is designed for the strip temperature in a combined direct- and indirect-fired strip Annealing Furnace. Based on a tailored first-principles dynamical model and the estimated current system state, the receding horizon controller selects optimal trajectories for both the fuel supply and the strip velocity so that the strip temperature is controlled to its desired target temperature. The controller additionally maximizes the throughput and minimizes the energy consumption. In the control algorithm, the dynamic optimization problem with equality constraints is numerically solved by using the Gauss–Newton method. The gradient and the approximated Hessian matrix of the objective function are analytically computed using an adjoint-based method. The capabilities of the proposed controller are demonstrated for a validated high-fidelity simulation model of an industrial Annealing Furnace.

  • a simple control oriented model of an indirect fired strip Annealing Furnace
    International Journal of Heat and Mass Transfer, 2014
    Co-Authors: Martin Niederer, Stephan Strommer, Andreas Steinboeck, Andreas Kugi
    Abstract:

    Abstract A simple mathematical model of an indirect-fired strip Annealing Furnace for real-time control and optimization purposes is developed. The considered Furnace is part of a hot-dip galvanizing line and is used for continuous heat treatment of steel strips. The heat that is released during the combustion process inside the radiant tubes is calculated by means of steady-state mass and enthalpy balances. For discretizing the heat conduction problem of the radiant tube wall and the Furnace wall, Galerkin’s method is used. Furthermore, simple heat balances are employed to model the temperature evolution of the guiding rolls and the strip. To facilitate an accurate representation of the strip temperature, the strip motion is described by Lagrangian coordinates. Heat transfer by conduction and radiation interconnects the individual dynamic submodels. Measurements from the real plant demonstrate the accuracy of the derived model, which is computationally rather inexpensive and thus suitable for model-based control and optimization.

  • a mathematical model of a direct fired continuous strip Annealing Furnace
    International Journal of Heat and Mass Transfer, 2014
    Co-Authors: Stephan Strommer, Martin Niederer, Andreas Steinboeck, Andreas Kugi
    Abstract:

    Abstract A mathematical model of a direct-fired continuous strip Annealing Furnace is developed. The first-principle model uses the heat balance to describe the dynamic behavior of the strip and the rolls. The mass and the enthalpy balance are employed to calculate the mass, the composition, and the temperature of the flue gas. The heat conduction equation of the Furnace wall is discretized by means of the Galerkin method. Furthermore, the convective and radiative heat transfer interconnect all submodels of the Furnace. For the calculation of the radiative heat transfer, the zone method is utilized. Finally, the assembled model is reduced by applying the singular perturbation method. A comparison of simulation results with measurement data from a real plant demonstrates the accuracy of the reduced model. Moreover, due to the moderate computational effort, the model is suitable for real-time applications in control and dynamic optimization.

Stephen W Taylor - One of the best experts on this subject based on the ideXlab platform.

  • Modelling steel strip heating within an Annealing Furnace
    Pacific Journal of Mathematics for Industry, 2017
    Co-Authors: Stephen W Taylor, Shixiao Wang
    Abstract:

    Annealing Furnaces are used to heat steel in order to change its chemical structure. In this paper we model an electric radiant Furnace. One of the major defects in steel strips processed in such Furnaces is a wave-like pattern near the edges of the strip, apparently due to extra heating near the edges. The aim of the paper is to model this effect and provide a way to calculate the elevated temperatures near the edges. We analyse two processes that are suspected to contribute to uneven heating. The modelling involves an asymptotic analysis of the effect of heat flux at the edges and a detailed analysis of the integral equations associated with radiant heat transfer in the Furnace.

  • development and validation of models for Annealing Furnace control from heat transfer fundamentals
    Computers & Chemical Engineering, 2010
    Co-Authors: N Depree, James Sneyd, Stephen W Taylor, Mark P Taylor, John J J Chen, Shixiao Wang, Moira Oconnor
    Abstract:

    Temperature in a continuous Annealing Furnace is studied by Furnace modelling using two methods. A 3D model is used to investigate the temperature distribution of the steel strip that is being annealed and the Furnace thermocouple probes, and information from the 3D model enables the construction of a highly simplified 1D/2D model, which predicts Furnace and strip temperatures with very good agreement to the 3D model. The simple model has a very short solution time and is suitable for rapid simulation of alternative Furnace operating conditions in order to optimise heat treatment quality, plant throughput and energy consumption.

  • Overheating Steel in an Annealing Furnace
    AIP Conference Proceedings, 2009
    Co-Authors: Stephen W Taylor, S. Wang
    Abstract:

    Annealing Furnaces are used to heat steel in order to change its microstructure and mechanical properties. The steel strips passing through such Furnaces must be heated evenly, otherwise defects in the product may occur. Such defects commonly occur near the edges of the steel.Annealing Furnaces have a high throughput and much thermal inertia so the occurrence of defects can potentially result in a large quantity of wasted product. Thus it is important to have a good mathematical model of this edge heating in order to explain how it occurs and to know what measures to take to avoid it.In this talk, we discuss such a model.

Xiaolong Li - One of the best experts on this subject based on the ideXlab platform.

  • monte carlo calculation of view factors between some complex surfaces rectangular plane and parallel cylinder rectangular plane and torus especially cold rolled strip and w shaped radiant tube in continuous Annealing Furnace
    International Journal of Thermal Sciences, 2018
    Co-Authors: Fei He, Li Zhou, Wu Li, Xiaolong Li
    Abstract:

    Abstract View factor plays an important role in evaluation of radiative heat transfer. This paper gives a detailed account of setting up the Monte Carlo calculation models of view factors between some complex surfaces. Main purpose is to calculate view factor between cold-rolled strip and W-shaped radiant tube in continuous Annealing Furnace. Given advantages of Monte Carlo method, it has been used to calculate view factor between the strip and radiant tube. Firstly, the Monte Carlo calculation models for view factor between rectangular plane and parallel cylinder and for view factor between rectangular plane and torus are established and verified, respectively. Then, according to reciprocity and superposition rules of view factors, the Monte Carlo calculation model for view factor between the strip and radiant tube is established by the above models. By comparing with analytical expression, or checking reciprocity after performing the Monte Carlo analysis in each direction between surface pairs, the calculation errors of above Monte Carlo models are analyzed and the results show that the Monte Carlo method is effective and reliable in calculating view factors between some complex surfaces.

Shahram Abbasi - One of the best experts on this subject based on the ideXlab platform.

  • new heating schedule in hydrogen Annealing Furnace based on process simulation for less energy consumption
    Energy Conversion and Management, 2008
    Co-Authors: Ahmad Saboonchi, Saeid Hassanpour, Shahram Abbasi
    Abstract:

    Cold rolled steel coils are annealed in batch Furnaces to obtain desirable mechanical properties. Annealing operations involve heating and cooling cycles which take long due to high weight of the coils under Annealing. To reduce Annealing time, a simulation code was developed that is capable of evaluating more effective schedules for Annealing coils during the heating process. This code is additionally capable of accurate determination of Furnace turn-off time for different coil weights and charge dimensions. After studying many heating schedules and considering heat transfer mechanism in the Annealing Furnace, a new schedule with the most advantages was selected as the new operation conditions in the hydrogen Annealing plant. The performance of all the Furnaces were adjusted to the new heating schedule after experiments had been carried out to ensure the accuracy of the code and the fitness of the new operation condition. Comparison of similar yield of cold rolled coils over two months revealed that specific energy consumption of Furnaces under the new heating schedule decreased by 11%, heating cycle time by 16%, and the hydrogen consumption by 14%.

  • computational and experimental failure analysis of continuous Annealing Furnace radiant tubes exposed to excessive temperature
    Engineering Failure Analysis, 2008
    Co-Authors: Ghasem Dini, Sayed Mahmoud Monir Vaghefi, Mostafa Lotfiani, Majid Jafari, Mohammad Safaeirad, Morteza Navabi, Shahram Abbasi
    Abstract:

    Abstract Radiant tubes of a continuous-Annealing Furnace at Mobarakeh Steel Company failed after a fraction of their rated service life. The tubes were manufactured from INCONEL alloy 601 superalloy. In this study, a failure analysis of the radiant tubes was performed by careful visual inspection of the failed tubes, scanning electron microscopy observation of crack region samples, energy-dispersive X-ray spectroscopy and X-ray diffractometer analysis of the tube metals and oxide scales. The temperature distribution for steady-state heat transfer and the structural stresses induced by the weight of the tube material were also studied in this paper. The finite element method (FEM) was employed to compute the effect of increasing temperature on tube service life and to define the critical regions. The experimental results showed that the mode of tube failure was a combination of creep damage and high-temperature oxidation attack which led to cracking. Significant growth of carbide precipitates was also observed in the failed zones; these precipitates result in both the drastic reduction of material ductility and the propagation of creep cracking. The simulation results showed that the damaged region in radiant tubes is susceptible to high-temperature creep. Tube failure occurred as a result of bending in the tube length, which may be responsible for subsequent hot-spot formations and high-temperature oxidation. Furthermore, the tube failure verified experimental results. Moreover, a simulation indicated that modification in radian tube installation is necessary because utilization of supports in specific locations can extend creep life.

Shixiao Wang - One of the best experts on this subject based on the ideXlab platform.

  • Modelling steel strip heating within an Annealing Furnace
    Pacific Journal of Mathematics for Industry, 2017
    Co-Authors: Stephen W Taylor, Shixiao Wang
    Abstract:

    Annealing Furnaces are used to heat steel in order to change its chemical structure. In this paper we model an electric radiant Furnace. One of the major defects in steel strips processed in such Furnaces is a wave-like pattern near the edges of the strip, apparently due to extra heating near the edges. The aim of the paper is to model this effect and provide a way to calculate the elevated temperatures near the edges. We analyse two processes that are suspected to contribute to uneven heating. The modelling involves an asymptotic analysis of the effect of heat flux at the edges and a detailed analysis of the integral equations associated with radiant heat transfer in the Furnace.

  • development and validation of models for Annealing Furnace control from heat transfer fundamentals
    Computers & Chemical Engineering, 2010
    Co-Authors: N Depree, James Sneyd, Stephen W Taylor, Mark P Taylor, John J J Chen, Shixiao Wang, Moira Oconnor
    Abstract:

    Temperature in a continuous Annealing Furnace is studied by Furnace modelling using two methods. A 3D model is used to investigate the temperature distribution of the steel strip that is being annealed and the Furnace thermocouple probes, and information from the 3D model enables the construction of a highly simplified 1D/2D model, which predicts Furnace and strip temperatures with very good agreement to the 3D model. The simple model has a very short solution time and is suitable for rapid simulation of alternative Furnace operating conditions in order to optimise heat treatment quality, plant throughput and energy consumption.