Convective heat transfer by cascading jet impingement in a batch coil annealling furnace

In a batch coil annealing furnace for annealing a plurality of wound steel strip coils stacked one on top of the other and positioned on top a base plate, said furnace having an outer cover and an inner cover with said inner cover sealed to said base plate to define a closed sealed annealing chamber containing said coils, a fan positioned beneath said base plate and said base plate having a plurality of diffuser openings in fluid communication with said annealing chamber for causing furnace atmosphere to circulate at high flow rates under pressure within said inner cover from either inside to the outside of said coils or from the outside to the inside of said coils, and an annular, convertor plate spacer between and vertically supporting said coils, the improvement comprising:

• said spacer having a plurality of vertically extending support bars upon which the exposed edge of said coils rest for supporting the weight thereof, said support bars radially extending from the inside of said coils to the outside thereof and circumferentially dividing said spacer into arcuate segments extending between adjacent support bars about said spacer;
• within each segment a plurality of radially spaced baffles, each baffle extending between adjacent support bars and vertically the distance of said support bars to define a plurality of radially extending heat transfer chambers, each baffle having a vertically centered, radially protruding recess formed therein and each recess having at least one orificing opening provided therethrough for fluid communication between adjacent heat transfer chambers whereby said furnace atmosphere is directed to flow against a baffle adjacent one of the coils' radial ends and through said orificing opening to impinge against the edges of said coil while flowing radially along said spacer through successive heat transfer chambers and during the course thereof forming a plurality of free standing gas jets impinging said coil edges.