A method for treating exhaust gas in an exhaust gas treatment device of a system may involve withdrawing exhaust gas from a processing device for mechanically and/or thermally processing an inorganic material of the system. The material to be fed to the processing device may be preheated by heat exchange with the exhaust gas. Further, a temperature of the exhaust gas entering the exhaust gas treatment device may be adjusted by adapting the exchange of heat between the exhaust gas and the inorganic material. In some examples, the exhaust gas treatment device may comprise an oxidation catalytic converter and/or a reduction catalytic converter.

The dry oxygen content in the exhaust of an industrial furnace may be controlled to 1% or less by determining one or more of: the temperature of: each or a group of one or more burner (flame); one or more section of the radiant walls adjacent (e.g., within 5 feet of the burner); the temperature gradient across the process coils; the combustion products of one or more burners; the mass flow rate or the volume flow rate of air to each burner (e.g., the pressure drop across the variable forced air aperture ii) comparing the result to said target value; and iii) adjusting either a) the opening of the variable forced air aperture; or b) adjusting the mass flow rate or the volume flow rate of air from said one or more fans.

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.