Flame front progress in gas assisted iron ore sintering. (25th January 2020)

• Record Type: Journal Article
• Authors: Tsioutsios, Nicos; Weiß, Christian; Rieger, Johannes; Schuster, Elmar; Geier, Bernhard
• Is Part Of: Applied thermal engineering. Volume 165(2019)
• Publication Date: 2020-01-25
• Subjects: Iron ore sintering -- Gaseous fuel -- Flame front speed -- Sinter strength; Heat engineering -- Periodicals; Heating -- Equipment and supplies -- Periodicals; Periodicals; 621.40205
• DOI: 10.1016/j.applthermaleng.2019.114554
• Languages: English
• ISSNs: 1359-4311

Abstract

Graphical abstract: Highlights: Control of flame front propagation in small-scale iron ore sintering studies. Partial substitution of the standard fuel coke breeze by a pulsed gas injection. Numerical modelling of the heat front travelling through the sinter bed. Lab-scale sintering tests with reduced coke breeze content in the sinter mixture. Abstract: The present paper is focused on the control of heat release and on the propagation of the flame front in an iron ore sinter bed. Small scale sinter experiments are performed in cylindrical packings of the sinter mix which are ignited at the bed surface and vertically passed by the suction gas. The heat front propagation is found to be closely linked to the consumption of the fuel mix in the sinter bed. Based on this findings, a dual fuel approach is explored whereas front propagation of the solid fuel combustion (coke breeze) is supported by pulsed injection of a secondary gaseous fuel. A non-stationary, one dimensional model is established to analyse the heat wave travelling in the sinter bed. The model setup describes a local thermal non-equilibrium between the sinter bed being defined as porous medium and the permeating gas. The model is based on the balance equations for the mass and heat transports caused by the solid and gaseous fuel combustion. Model calculations support the experimental findings and demonstrate that satisfying sinter peak temperature levels and locally focused energy release are ensured by combined solid fuel burnout and high temperature gas combustion. During some lab-scale sintering tests, coke breeze content was reduced in the sinter feed mixture, and secondary fuel gas was supplied in pulsed mode to compensate the missing energy demand. The flame front speed as well as properties related to the sinter quality such as the tumble and shatter strength were determined, with the later index showing more sensitive results. The investigations demonstrate that pulsed methane injection can increase the flame front speed compared to the pure coke case with 5.1 wt% coke., the pulsed gaseous fuel combustion can nearly compensate the strength loss for a moderately coke reduced rawmix with a coke content of 3.5 wt%.