(58z) New Air Assisted Flare Design to Handle Low Flow Rates of Waste Gases

Hayder A. Alhameedi ^a, Joseph D. Smith ^b

^a Department of Chemical and Biochemical Engineering, Missouri University of Science and Technology, Rolla, MO 65409-1230. USA, +1 (573) 612-8911, haa6hb@mst.edu

^b Department of Chemical and Biochemical Engineering, Missouri University of Science and Technology, Rolla, MO 65409-1230. USA, +1 (573) 341-4294, smithjose@mst.edu

Abstract

Flares systems in chemical and petrochemical plants are used as safety equipment to relieve pressure in plant equipment to avoid explosions and prevent air pollution. These flares are fed at lower flow rates of waste gases than they were designed for. Current EPA regulations limit the exit gas velocity to less than 60 ft/s, but do not consider the lower velocity limit required to ensure complete combustion. Gases exiting a flare tip at low flow rates result in insufficient mixing with ambient air and leading to smoking conditions and excess emission. This reduction causes a decline in combustion efficiency and decreases the flare performance. The main objective of this study is to design and test a new air-assisted flare capable of efficiently operating over a wide range of low flow rates of waste gases. In this work, a flare system consist of a 6-inch diameter have been used to evaluate various flare tip designs capable of operating at low flow rates with high flare performance. A special flare tip has been designed with waste gases to increase the flow rates of these gases. As a result of reducing exit area for waste gases, the flow rate of these gases increases. This work relies on CFD analysis to design the flare tip. Experimental tests have been conducted to validate the CFD model and examine different operating scenarios expected in the field during normal operating.