High Performance Industrial Furnace Development Project has been proceeding by JIFMA entrusted from NEDO to clear 30% reduction of energy, 20% downsizing and very low NOx. We achieved completely the targets and verified the performance in as many as 150 examples of practical plants which are variety of reheating furnaces, heat treatment furnaces and melting furnaces in the field test project. Central to this combustion technology is high temperature air combustion technology using regenerative combustion system that preheats the air fed into the combustion furnace to over 1, 000°C, much higher compared with before and jets fuel into this high speed turbulent flow, then this means to preheat air over auto ignition temperature of fuel properties and to combust diluted by ample exhausted gas. This technology has many functions to eliminate local high temperature regions, to reduce temperature differences in the furnace, to attain high efficient heat transfer through an increase of the mean temperature inside the furnace without any local high temperature to optimize heating algorithm by some independent heat control mechanism and to control NOx by heating control. We describe combustion characteristics in high temperature air combustion compared with conventional combustion.
High temperature air combustion that uses regenerative burner has many characteristics as follows, (1) Self ignited combustion, (2) Unnecessary for flame holding measure, (3) The state and shape of flame has remarkable change by how to mix fuel and air, (4) Notwithstanding using highly preheated air, instantaneous maximum flame temperature is low, (5) Flame temperature fluctuation is small, (6) Diluted combustion by burned gas or low oxygen combustion generates, (7) Reaction zone thickness in low oxygen combustion becomes thick. Report (I) shows high efficient heat transfer based on temperature raising, then this report (II) shows the characteristics of temperature equalization and low NOx.