Electric resistance furnace

摘要

The furnace has a center furnace body that comprises a heat insulating unit, and a preheating unit provided at a gap from the surface of the center furnace body. The preheating unit (10) comprises a unit provided on an inner wall surface of a cylindrical heat-insulating unit. The heat insulating unit is located at an upper surface and a lower surface of an outer heat insulating unit (11) located around preheating unit.