How should furnace layout be specified for industrial heating elements?

Divide the effective heated zone, workpiece cross-section and door heat loss into power sections so that watt density matches the radiation geometry of the lining and the spacing between elements, avoiding local overheating or under-temperature. Choose sheath diameter, material and protection grade according to furnace atmosphere, dew point and maximum working temperature; for corrosive or dusty atmospheres, use a resistant sheath and lower the watt density. Spacing must allow both air circulation and access for withdrawal and maintenance, and elements near the door and side walls can be placed closer to offset heat loss. Use multiple thermocouples with independent zone control and some reserve capacity. At acceptance, perform no-load and full-load temperature mapping and measure insulation and cold resistance; one sensor reading never proves whole-furnace evenness, so judge by the deviation across all measuring points.