Experimental Study Of Premixed Combustion In Porous Media Burner

Reduction of pollutant emissions is one of the most important goals of combustion research today because of energy shortage and environmental pollution. The concept of "superadiabatic combustion" was proposed by some scholars to solve these problems. Porous media burners which are based on "superadiabatic combustion" have been the focus substantial attention in the past few years due to their potential to produce low emissions over a wide operating range.The aim of this work is to put the technology of combustion in porous media into industrial applications. A porous burner used for a furnace has been developed according to the characteristics of porous media and industrial practical needs. The premixed combustion in porous inert media has been experimentally studied. The experimental method and the numerical simulation method are used to compare the effects on the same operating conditions of porous media burner and the general burner. The results are used to guide industrial applications.The industrial application experiments of the porous burner indicate that the porous burner which is designed in this research is feasible for industrial applications. The burner can keep working stably for a long time when a series of measures to prevent flashback are taken. In the current material conditions, it is explored that the firing rate should be blow1200kW/m2and in this case the radiating surface temperature of the porous media is no more than1200℃. Characteristics of porous media such as the pore size, the high temperature and the thermal shock resistance are all the key factors for industrial applications. Flue gas analysis show that the porous burner gives very low emissions. Compared the effects on the same operating conditions of porous media burner and the general burner with experimental methods, the results show that the thermal efficiency of the porous media burner is higher than the general burner more than5%. This further illustrates it could achieve the effect of energy saving and low emissions with a porous media burner in the actual production. A self-built test furnace with natural gas as fuel is taken as the research model. A three-dimensional mathematical model has been developed for the coupled analysis in a non-steady state of fluid flow and heat transfer in the furnace with commercial package FLUENT when the porous burner and the ordinary burner are used respectively. The results of numerical simulation and experiment are consistent.In this work, the premixed combustion is taken into account. Based on the chamber furnace of Baosteel with preheating combustion air, the structure of the burner has been improved as follows:first, the twisted tape is increased to facilitate the gas mixture more effectively; second, two mixing boxes are set to ensure safety. Changes in gas pipe of the shut-off valve diameter to allow the hot air of smaller influence. The experiment results show that the new structure burner’s performance at ensuring stable combustion is satisfactory. However, due to the limitation of materials and in order to keep stable combustion for a long time, the following points should be taken into account:(1) the flame stabilization position in porous media should be as close as possible to the porous media outlet;(2) in the actual application, the luminous flame, rather than incandescent flame, should be kept at the outlet surface of the porous media.