Mohsen Kazemimanesh, Larry W. Kostiuk, D Nobes, Jason S. Olfert (Department of Mechanical Engineering, University of Alberta) and Matthew R. Johnson (Department of Mechanical & Aerospace Engineering, Carleton University)
2012
# 09-9181-50
Abstract
This research is an exploratory investigation into the effects of non-hydrocarbon liquids on flare gas phase and particulate emissions. The flaring process was simulated using a 9.45 mm diameter, natural gas diffusion flame with a 65 mm diameter co-flow air where liquids are introduced into the fuel stream using an ultrasonic atomizer. Various liquids were tested including distilled water and water with sodium chloride (to represent the naturally occurring saline water found at upstream oil and gas sites). Two flow rates of natural gas were considered: 0.3 standard liters per minute (mean velocity of 0.07 m/s) and 0.8 standard liters per minute (mean velocity of 0.2 m/s). The higher flow rate case was above the smoke point for the flame and produced soot particles in the exhaust. An ultrasonic nozzle was used at the base of the stack to inject liquid droplets into the fuel stream. The focus of this exploratory research was to measure the size and number concentration of the emitted particulate matter (PM). Particle size distributions were obtained using a Scanning Mobility Particle Sizer (SMPS) for each flow condition, with and without liquid droplets injected into the fuel stream. The results showed that particulate matter emissions were orders of magnitude higher when salt water was present during the combustion of natural gas. Gas phase emissions were measured for the case of sooting diffusion flame using a portable gas analyzer. Results showed a decrease in soot and NOx emissions when distilled water was present in the fuel stream. Results also revealed that NOx emissions decreased and particulate emissions significantly increased when salt water was added to the flow, however, the additional particles did not appear to be soot. In addition, a sharp increase in hydrocarbon emissions was observed when salt water was combusted in the flame due to incomplete combustion. Moreover, investigation of volatility of particulate emissions when non-distilled water was present in the fuel stream showed that these particulate emissions are nonvolatile.