Simplified flare combustion model for flare plume rise calculations

Abstract

The dispersion of plumes released from stacks depends on wind speed, plume emission rate, stack height, and other meteorological and stack variables. Plume rise is an important aspect of plume dispersion because it increases the apparent release height, which leads to lower ground-level concentrations. Plume rise linked with flare combustion has received only minimal attention in the literature to date, despite its importance. This study develops a numerical model of plume rise with flare combustion based on material, heat, mass, and momentum balances. The basis of the model is a numerical plume rise model used in CALPUFF to model plume rise of large buoyant area sources, and is also used in PRIME (plume rise model enhancements), which models building downwash. The proposed model considers the reaction kinetics. The competition between CH 4 and CO combustion causes a modification of the temperature profile of up to 3 % in comparison with an instantaneous reaction model. Moreover, emissivity, which plays an important role in the heat conservation equations but which was only parameterized in an earlier work, is calculated more directly to increase the accuracy of the model. It was found that soot is the main contributor to flame emissivity. Finally, the air dispersion model CALPUFF was run according to the proposed flare model and an empirical flare model by Beychok to compare results of the models. This new flare method is sufficiently simple to be embedded into air dispersion modelling software such as CALPUFF.

Local air pollution from oil rig emissions observed during the airborne DACCIWA campaign

“…Very recent attempts to model such flames (Aboje et al, 2017;Damodara et al 2017) showed the influence of the composition of the natural gas and the validity of the chemical kinetic mechanism are of primary importance to predict the emitted species. Moreover, the flame characteristics such as temperature, height, and length, have a strong impact on the dispersion of the plume together with wind speed and other meteorological variables (Rahnama et al, 2016). All these parameters need to be taken into account when considering air field campaigns.…”

Quantitative analysis of enclosed ground flare based on PHAST analysis

“…4 Wang et al 5 analyzed receptor configuration and measurement noise through numerical example analysis based on process hazard analysis software (PHAST). Rahnama et al 6 established a numerical model of the rise of flare combustion plumes based on matter, heat, mass, and momentum balance, which can be used to simulate the rise of plume flow in large area buoyancy sources. Wang et al 7 conducted a risk analysis on PHAST, according to the corresponding thermal radiation hazard standard.…”