Aluminum Coil Annealing Furnace Featuring High Convection Vortex® Jet Airflow
SECO/WARWICK offers custom engineered aluminum annealing furnaces for coil and foil rolls. Furnace capacities range from single coil furnaces to multi-zone furnaces with tight zone control.
Using patented Vortex jet airflow technology, SECO/WARWICK’s Vortex® aluminum coil annealing system, combined with optional Bypass Cooler and SeCoil® control and simulation software, provides coil producers the ability to significantly reduce the overall cycle time of their furnaces, resulting in energy savings, increased productivity, and improved surface quality. Annealing efficiency is improved by an increased heat transfer coefficient achieved by high-speed air impinging on both sides of the coil, compared to processes which heat only through the outside layer of the coil.
The optimal aluminum coil annealing furnace design shortens the cycle time as much as possible while still attaining the desired metallurgical properties over the entire load.
Vortex® Jet Heating System
The effective thermal conductivity in a strip coil is much lower in the radial direction than in the axial direction, therefore, the most effective way of heating the coil is through the edges of the coil layers. The difference between the thermal conductivity for the two directions is caused by the heat-insulating effect of the gas between the coil layers. Coil winding force also plays a crucial role in the process. The Vortex Jet Airflow Heating System incorporates an array of nozzle jets oriented to generate a spiral vortex in the furnace atmosphere, be it air or shielding nitrogen, enabling superior heat transfer without generating hot spots in the coil. The high velocity atmosphere circulation allows heat to quickly and evenly penetrate the coils for complete annealing.
Infrared image analysis demonstrates the Vortex Jet Airflow Heating System achieves a more uniform coil surface temperature for the duration of the heat treat cycle compared to conventional coil annealing systems. Heat transfer coefficients up to 150W/m2K enable faster load heating and shorter cycle times compared to a 110 W/m2K heat transfer coefficient of standard straight burner nozzle configuration.
Bypass Cooler
SECO/WARWICK’s proprietary annealing furnace bypass cooler design provides cooling under a protective atmosphere. Cooling is very important in this application for both metallurgical and handling considerations. The coolers use an internal bypass arrangement which limits the temperature of the atmosphere going through the heat exchangers to a maximum of 175°C, preventing oils residues on the coil from baking onto the fins of the heat exchanger. The coolers are designed to provide in-depth, programmed, or auxiliary cooling and are available in standard or custom sizes. The coolers can be rear-or side-mounted depending on available floor space. Additionally, users can retrofit bypass coolers to compatible existing annealing furnaces. Our newest bypass cooler design even eliminates the need for any foundation pit.
SeCoil® process control and simulation software
SeCoil® is our process simulation and control software created to predict heating treating process outcomes and to control furnaces through subsequent heat treat processes.
The mathematical model considers all the numerous parameter variables, such as temperature and outlet velocity of the heating medium, type of alloy, sheet thickness, and roll dimensions, and uses the data to predict the temperature at any point inside the coil. With the SeCoil® simulator you can even simulate the heating curve of any point of the coil, serving as a virtual thermocouple. The SeCoil® simulator provides knowledge about the thermal state of the coil at any time during the process. It may, therefore, be used in many ways, including for forecasting heating curves for different types of coil and process conditions (furnace temperature, mixer efficiency) and for continuous control of the annealing process without the need to use batch thermocouples (controller). The meta-model was created using artificial intelligence methods (behavioral modeling), and can be an alternative or a supplement to a simulator based on phenomenological modeling. In contrast to the phenomenological model, the behavioral model applies only to the tested system and within the assumed limits of operating conditions. However, its accuracy for the analyzed range of data may be greater than in the case of the phenomenological model.
From a metallurgical point of view, the critical process parameters are the final batch processing temperature and the soaking time, which define the process of recrystallization annealing and must be met precisely. As such, the SeCoil® automatic regulation and control system has two main tasks: to maintain, for the longest time possible, an adequate air-to-work (head) temperature to minimize heating time and after reaching the load temperature setpoint, to reduce the head temperature to avoid any overshot of the load setpoint.
From an economic point of view, the most important parameter is the total process time, which directly affects energy consumption. Due to SECO/WARWICK’s unique system, shorter process time can be achieved without the risk of overheating the load. After the operator enters process and coil parameters the system can then simulate the process and the collected data can ultimately be used to fine-tune the recipe and optimize the process time before processing begins.
/ High-Efficiency Process
Process efficiency can be significantly improved compared to traditional annealing systems – without local overheating.
/ High Quality Process
Improves aluminum properties especially at edges and minimizes cracking or staining of milling oil.
/ Lower Cost Operation
Uses less electricity for gas circulation.
/ Flexible System Design
Various coils diameters, widths, sheet thicknesses.
/ High Heating Head
Possible to use heating head even up to 150°C.
/ Coil and Foil Application
Aluminum foil from 120mic and thicker can be processed
/ Annealing
/ Homogenizing
/ Automotive
/ Building
/ Packaging
/ increases productivity while reducing energy consumption
/ utilizes burners with an auto-recuperator with up to 86% energy recapture, as well as ecological insulation with a properly selected thickness to optimize heat loss through the walls,
/ the use of the innovative SeCoil® tool allows for shorter coil annealing process times, saving energy and media consumption,
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