design desirable conditions for inlet and outlet ports to establish mild regime in a heat treatment furnace

The aim of this work is to design a desirable condition for the ports of the inlet air and outlet to establish the mild regime in a lab-scale pre-heat furnace of the steel. the furnace is scaled down from 7mw to 10kw by the constant residence time approach to facilitate the design. in the initial furnace design, one fuel port was installed on the center of the vertical furnace surface along with four inlet air ports around it, and four outlets around of inlet airs. the target ingot temperature of 1250°c and the ingot temperature uniformity is considered for the work’s main target points. reduction in air mass flow rate of the bottom port leads to increase the ingot temperature from 1164°c to 1174°c, as a result of increasing the averaged gas temperature and increasing the mixing rate. the reduction in the diameter of the top outlet gives the close results to the air reduction, which reduce the damköhler number and increase the residence time. all cases have a local mild regime but the air and outlet reduction expand the mild regime zone, and effects of the air reduction is more than outlet reduction.