Thermal treating apparatus and process

A thermal treating apparatus providing convection thermal transfer between a uniform flow of treatment fluid and articles being treated, comprising:

• an elongated treatment chamber;
• means for passing articles being treated in-line along the axis of said treatment chamber from a treatment upstream end portion to a treatment downstream end portion;
• a recirculation plenum exterior to said treatment chamber, said recirculation plenum having a recirculation plenum upstream end portion in fluid communication with said treatment downstream end portion of said treatment chamber and a recirculation plenum downstream end portion in fluid communication with said treatment chamber through distribution means providing decreasing cross sectional area from said treatment upstream end portion along at least a portion of the length of said treatment chamber to deliver treatment fluid at a plurality of locations along at least a portion of the length of said treatment chamber;
• a blower in said recirculation plenum to pass said treatment fluid through said treatment chamber and said recirculation fluid through said recirculation plenum;
• and thermal control means in said recirculation plenum to add or extract thermal energy to change said recirculation fluid to a desired thermal state for said treatment fluid.