Lecture: Oxy-coal combustion research at the University of Utah: Flame ignition and fly ash deposit studies
Speaker: Jost O.L. Wendt， Presidential professor at the University of Utah
Time: June 8th, 2011,14:00 pm-16:00 pm
Venus: F307,Mechanical Building A
Inviter: associate  professor. Zhou-Yue gui(TEL:34206769)

ABSTRACT：
In order to retrofit oxy-combustion to existing coal fired boilers it is necessary to predict accurately the changes in combustion and heat transfer caused by changes in oxidant from air to mixtures of recycled flue gas and oxygen. These changes cause: (1) Changes in near field flame aerodynamics at the burner; (2) Changes in ash aerosol and deposit formation. For the near field aerodynamics, results presented here focus on the relationship between the flame shapes as seen by an observer, to the PDF’s used to quantify the fluctuating flame standoff distance. The latter was taken to be an essential characteristic of the near field aerodynamics of oxy-coal flames. Flame images (yielding practical, but qualitative information) and the concomitant PDF’s (yielding fundamental, and quantitative data) are presented showing the separate effects of primary PO2, secondary PO2, transport diluent composition et. al. Flame ignition differed between two bituminous coals of similar ultimate and proximate analyses, but different volatilization profiles. For ash aerosol and deposition mechanisms, results presented here show that less soot is formed under oxy-coal conditions than under air fired conditions, that much of the ultrafine particle mass consists of soot, but other than that, with pure CO2 as the recycled gas, changes in the size segregated ash aerosol composition are small. In spite of this, data suggest that oxy-coal combustion can have significant impact on deposit chemistry, due either to changes in flue gas environment, or to changes in particle deposition efficiencies. On the other hand, for a given over-all oxy-coal combustion condition, the recycled flue gas composition (water, SO2, and particulate content) does have large effects on the ash aerosol particle size distribution.

Intruduction of speaker:
Jost O.L. Wendt is Presidential Professor in the Chemical Engineering Department at the University of Utah. Previously he was Head of Chemical and Environmental Engineering at the University of Arizona, USA. Jost obtained his Ph.D. and M.S. in Chemical Engineering from the Johns Hopkins University, Baltimore, MD., and his B.Sc. in the same subject from the University of Glasgow in Scotland. He is Past Chair (2009) of the Environmental Division of the AIChE, Fellow of the AIChE and has 40 years of experience in theoretical and experimental combustion research. He is the recipient of the 2004 Lawrence K. Cecil Award, the 2009 Pioneer Award by the ASME/IT3 and was an Eminent Visitor to the University of Newcastle, Australia, in 2002. In 2009 he was awarded the Bianzhong or “Chime Bell” Prize for Service to Hubei Province, China. The author of over 100 peer reviewed papers and over 250 presentations, Jost is internationally recognized for his wide-ranging research on reduction of emissions from combustion processes. His research within academia, industry and EPA laboratories, has led to ‘reburning’ for NOx control, to mitigation of waste incinerator emissions through control of ‘transient puffs’ and ‘rogue droplets’, to the management of fine particle and toxic metal emissions using sorbents. He is currently active in oxy-coal combustion and mercury sequestration technologies.