Flame Propagation Model and Combustion Phenomena: Observations, Characteristics, Investigations, Technical Indicators, and Mechanisms

Abstract

Critical conditions are usually obtained for ignition in a self-heating solid system consisting of two components generating heat independently, one component being inexhaustible and the other exhaustible by either simple first order or autocatalytic reaction. Ignition depends upon whether the exhaustible component can cause a temperature rise in excess of the upper stationary, but unstable, value possible for the inexhaustible component reacting alone. The system provides a theoretical model for some commonly occurring examples of self-heating and ignition in porous solids containing oxidisable oils. It is shown that: (a) the ignition criterion of the model, which involves a nonarbitrary critical temperature increase, has a high degree of physical reality; (b) the model is, in principle, capable of predicting ignition from primary kinetic and thermal data; (c) itis likely to be possible often to make a reliable prediction of critical size for self-ignition in a two-component system at ordinary atmospheric temperatures by a simple extrapolation from small-scale ignition data, obtained at higher temperatures, in the same way as for ignition due to a single reaction. Examination of both adiabatic and non-adiabatic flame theories showed that a 'steady state' exists only under the special condition that a heat sink exists at the initial temperature. For the general case of freely propagating, non-adiabatic flames only a quasi-steady state can be achieved. Subject Matter and DiscussionThe papers on ignition cover too wide a range of subjects to permit detailed discussion on average seven minutes allotted for flame analysis. It seems more appropriate, therefore, to discuss them according to the method of approach to solution of the problems of ignition. Two of the papers [1,2] are theoretical treatments in which simplifying assumptions are made to permit analytical solutions to be found. Such treatments are valuable if the factors neglected are in fact unimportant, otherwise they are of value only as mathematical exercises. In this connection, we would like to ask whether there are any examples of pure thermal explosions apart from those treated by Varatharajan and Williams [3].

Design and simulation of a utility oilfield flare in Iraq/Kurdistan region using CFD and API-521 methodology

“…To avoid the flame's lift off, the USEPA has suggested that the flare tip velocity should be less than the maximum allowable flare tip velocity determined by the flare tip diameter, the density of the flared vent gas and the air and combustion zone gas composition. The key factors important in determining the flare flame stability includes flame speed, flammability limits and ignition temperature [ 18 , 19 ]. The ambient wind velocity also affects the flame size and shape and can affect the heat radiation from the flame [ 19 , 20 ].…”

“…The key factors important in determining the flare flame stability includes flame speed, flammability limits and ignition temperature [ 18 , 19 ]. The ambient wind velocity also affects the flame size and shape and can affect the heat radiation from the flame [ 19 , 20 ].…”