Convection ovens use fan pressure, as well as natural convective force, to circulate heated air within an insulated enclosure. Typically gas fired, convection ovens can be direct-fired or indirect-fired. Direct-fired ovens circulate air directly through a flame; indirect-fired ovens circulate the air through a heat exchanger in contact with a flame. An indirect-fired oven is usually recommended in instances where the products of combustion may interfere with the process, for example, bright white coatings. In these instances, electric resistance ovens can also be used but are typically limited to small batch ovens due to energy cost.
The amount of air circulated in the oven relative to the oven volume and the supply and return duct design rate are the primary determiners of the temperature regime in the oven. The time-temperature curve or "oven profile" is matched to the process. For example, liquid coatings should heat up slowly to allow solvents to escape before the coating "skins" over. However, powder suppliers generally ask for a temperature profile that abruptly rises then levels off at the maximum temperature before falling abruptly at the exit. The amounts of air and duct design also determine the temperature variation within the product envelope, how easy it is to change the profile and how energy-efficient the oven operates.
The oven exhaust rate and air seal are also key elements of the oven's energy efficiency. ADAL employs VFD control of the exhaust in order to adjust the rate to minimize heat loss yet meet process requirements.
Our air seals feature adjustable air knife slots on horseshoe duct coupled with a heat trap fan intake that effectively segregate the oven from the outside atmosphere. Bottom-entry ovens are used where practical for the greatest energy efficiency by trapping heat in the oven and eliminating air seal fans.
ADAL convection ovens are designed to meet your specific part and process requirements but flexible enough to meet your future demands. The following convection oven features are available:
• Dry-Off, Pre-Heat, and Cure
• Natural Gas, Propane, Electric
• Direct or Indirect Fired
• Energy Efficient VFD on Exhaust
• Heat Recovery and Reuse
• Heavy-Duty Construction
• Fine Tuned, Adjustable Even Air Distribution
• Internal Structural Frame with High Temp Paint
• T&G Panels, Mineral Wool w/ Aluminized Skins
• Clean ability features for Class A Finish
• Circulation Air Filtration
• Ovens Constructed Inside or Outside Plant