ME DEPARTMENTAL SEMINAR

Friday, November 5, 2004

1:00pm – 2:00pm

2233 GG BROWN

Professor Arvind Atreya

Department of Mechanical Engineering

University of Michigan

“Radiative Homogeneous Combustion for Improved Efficiency and

Reduced Emissions”

Abstract:

The problem of “how to configure combustion in industrial furnaces to increase efficiency and reduce emissions” is perhaps not the most fashionable but it is very important from both economic and environmental point-of-view. According to the recent DOE data, energy intensive industries like steel, aluminum, glass, metal casting, etc., consumed about 12 Exajoules of energy per year in the US alone costing about $50 billion. This also resulted in some 150 million metric tons of carbon emissions to the atmosphere among other pollutants. However, the useful portion of this energy was less than 60% and over 40% was lost. This significant amount of lost energy (~5 Exajoules costing about $20 billion) and the corresponding carbon emissions (~60 million metric tons of carbon emissions) need to be reduced.

To examine possible solutions to this problem, a laboratory-scale furnace has been constructed with the objective to highly preheat the incoming oxygen-enriched air and fuel with the wasted flue gas enthalpy. While simple, this is often not done because it increases the NOx production rates and contributes to heat flux non-uniformities within the furnace. A novel solution to this problem is proposed where exhaust gas recirculation, intense flame radiation and increased residence time are employed to reduce the flame temperature and thus thermal NO. Nearly homogeneous burning occurs in distributed reaction zones under slightly rich conditions that enable increasing the flame radiation and also promote NO reburn reactions. The aim is to obtain near unity flame emissivities at temperatures not exceeding 1900K and providing nearly uniform radiation heat flux at a magnitude exceeding 400kW/m², while maintaining strict constraints on NOx, CO, unburned hydrocarbons and particulate emissions. This level of heat flux enables an increase in the furnace productivity or a decrease in size and cost.