An apparatus for the thermal heating of steel products that includes inside it a path for feeding the steel items which extends between an entry end and an exit end of the steel items, a mechanism for feeding a fuel, and a mechanism for feeding a comburent including oxygen, and burners able to operate the combustion of the fuel and of the comburent.

A jet-type direct-fired preheating system, comprising a direct-fired furnace and a preheating furnace. The direct-fired furnace comprises a furnace casing, a direct-fired heating area being provided in the furnace casing. The preheating furnace comprises: a furnace body, wherein the upper portion of the furnace body is connected to the upper portion of the direct-fired furnace by means of a communicating pipe, the bottom of the furnace body is provided with a strip steel inlet, a sealing apparatus and a steering roller, an upper collection chamber of direct-fired waste gas and a secondary combustion chamber of direct-fired combustion waste gas are provided at the upper portion in the furnace body, and a lower collection chamber of the direct-fired waste gas is provided at the lower portion in the furnace body; and a plurality of heat exchange and jet bellows units, provided in the furnace body in the height direction of the furnace body, a threading channel being formed in the middle. Each heat exchange and jet bellows unit comprises: a bellows body, a heat exchange pipe being provided in the bellows body, and a nozzle being provided on the side surface opposite to the threading channel; a secondary waste gas mixing chamber provided between the bellows bodies; and a circulating fan, an inlet pipeline port being formed in the threading channel, and an outlet pipeline port being located in the bellows body. According to the present invention, strip steel can be quickly preheated to 350 or above and quickly heated to 750 or above; and waste heat of the waste gas is fully utilized, such that an over-thick oxide layer can be prevented from being generated on the surface of the strip steel.

The invention provides a heat treatment furnace with stable conveyance, including a furnace body, a conveyance mechanism, a carrier locking mechanism, and a carrier unlocking mechanism. The furnace body is provided with an isolation zone, a drying zone, and a cooling zone in a product conveyance direction. The isolation zone, the drying zone, and the cooling zone are jointly provided with a product channel which extends through the furnace body. The drying zone includes at least one drying box body. Circulating heating modules are symmetrically disposed on two sides of each drying box body. The conveyance mechanism includes a carrier bearing surface. The carrier locking mechanism is arranged on the carrier bearing surface, and is used for locking the carrier on the carrier bearing surface. The carrier unlocking mechanism is at least arranged at an outlet of the product channel, and used for releasing the locking of the carrier.