Exhaust gas treatment furnace, and exhaust gas treatment device in which exhaust gas treatment furnace is used

An exhaust gas treatment furnace that thermally decomposes an exhaust gas, comprising:

• a furnace body that has a sealed vertical tubular shape, and that includes a gas treatment space formed inside and a gas discharge port formed in a center part of a wall surface of a bottom thereof;
• a long electric heater that is hung from a center part of a surface of a ceiling of the furnace body and that heats the gas treatment space;
• and
• a ceramic inner tube member of which a rear end portion is mounted on a surface, on an inner side, of the bottom of the furnace body so as to enclose a circumferential edge of the gas discharge port, and of which a front end portion is open at a position close to the surface of the ceiling of the furnace body and encloses an outer circumference of the electric heater,
• wherein a gas introduction port is formed in one of a wall surface of the ceiling and the wall surface of the bottom of the furnace body, in such a manner that the exhaust gas inside the gas treatment space flows along an axial direction on an outer circumference surface side of the ceramic inner tube member, then reverses, and flows along the axial direction on an inner circumference surface side of the ceramic inner tube member.