Numerical Study of Smoke Emissions of an Air-Assisted Elevated Flare

Abstract

In the petroleum industry, flares are used to burn off unwanted waste gas generated during upstream processes. For elevated flares where a huge amount of waste gases is gathered and burned at a single flare header, visible smoke emission is a common problem. It is known that smoke emission is a complex thermochemical process and is affected by many factors. To suppress smoke production, air or steam is often injected into the header to supply additional oxygen and enhance mixing. In this paper, computational fluid dynamics (CFD) is used to study the smoking behavior of an air-assisted elevated flare of a domestic petroleum company. The Moss-Brookes model is used to simulate the soot generation. The impacts of fuel composition, fuel flow rate, and crosswind are investigated by varying the fuel type, waste gas mass flow rate and crosswind speed. Our results suggest that soot concentration is strongly affected by the fuel composition and flow rate. The crosswind speed also greatly affects the flame shape and size and the overall soot generation.