Industrial furnace and method of utilizing heat therefrom

A continuous industrial furnace comprising:

• an inlet;
• a heating zone, a cooling zone;
• and an outlet in this order, the continuous industrial furnace being configured to heat-treat a workpiece while conveying the workpiece from the inlet to the outlet,
• wherein at least a part of the heating zone comprises a furnace wall heat insulation structure, the furnace wall heat insulation structure comprising:
• an outer wall having one or more gas introducing ports;
• and a porous thermal insulation layer having a lower surface and an upper surface, and defining a gap between the upper surface thereof and an inner side of the outer wall;
• wherein the heating zone further comprises one or more exhaust ports for sucking and discharging the gas after the gas flows into the heating zone of the furnace from the gas introducing ports through the gap and the porous thermal insulation layer in this order and then flows toward the inlet side;
• wherein at least a part of the cooling zone comprises the furnace wall heat insulation structure;
• wherein the lower surface of the porous thermal insulation layer contacts an outer surface of the heating zone continuously along a length thereof;
• wherein the at least one side surface of the porous thermal insulation layer contacts at least a portion of an outer surface of the cooling zone;
• wherein an inflowing gas in the gap defines a gas layer covering the upper surface of the porous thermal insulation layer;
• and
• wherein the cooling zone further comprises one or more exhaust ports for sucking and discharging the gas after the gas flows into the cooling zone of the furnace from the gas introducing ports through the gap and the porous thermal insulation layer in this order and then is utilized for cooling the workpiece.