Abstract View
Effect of Deionized-water and Steam Addition on Soot and NOx Emissions in a Lab-scale Flare
OLANREWAJU WASIU BELLO, Milad Zamani, Larry W. Kostiuk, Jason S. Olfert, University of Alberta
Abstract Number: 47
Working Group: Combustion
Abstract
Steam-assisted flares are often used in the upstream oil and gas industries as a strategy to produce “smokeless” combustion. Unheated liquid water addition to flames is also known to suppress soot formation but is rarely used in industrial flares. Since utilizing unheated liquid water saves the energy cost used to convert water to steam, it is useful to investigate the extent to which unheated water and steam individually affect soot formation and NOx emissions during flaring.
Measurements of the combustion products of a lab-scale flare were carried out using a photoacoustic extinctiometer, a chemiluminescence analyzer, and a non-dispersive infrared gas analyzer to measure black-carbon mass concentration, NOX concentration, and CO2 concentration, respectively. In addition, a Scanning Mobility Particle Sizer (SMPS) was used to characterize the concentration and the mobility diameter of the emitted particles. The three fuels used in this study were pure propane, pure methane, and a mixture of 90% methane and 10% propane; the latter one approximates a typical higher heating value of Alberta flare gas. The fuel flow rates were fixed at 20 SLPM in all cases, and deionized-water and steam were entrained into the combustion zone, while their flow rates varied from 0 to 30 grams per minute.
The result shows that both deionized-water and steam reduce NOx and soot emission indices; however, deionized-water reduces NOX and soot emissions more than steam. Likewise, the total particle number concentration decreases with an increase in deionized-water and steam, and deionized-water reduces the total particle number concentration more than steam at the same flow rate. These results suggest that water-assisted flares in the oil and gas industries would produce lower emissions with a lower operating cost compared to steam-assisted flares.