(54r) The Effects of Oxygen Enrichment on the Explosibility Properties of Flammable Gases and Vapors

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THE EXPLOSIBILITY PROPERTIES OF FLAMMABLE GASES AND VAPORS

Abstract

In the chemical industry, “nascent” oxygen is involved in the creation of partial-oxidation products, including many pharmaceutical compounds. The oxygen could initially be in the form of peroxides, such as hydrogen and sodium peroxides, and also as chlorates and perchlorates, periodates, nitrates, and dichromates. The vapor space in oxidation reactors could contain high concentrations of oxygen gas, in combination with the flammable vapors of organic compounds and, preferably, with inert gases such as nitrogen. To evaluate the possible explosion hazards of such mixtures of fuel and oxidizer, it is important to determine the explosibility properties of organic compounds in atmospheres containing high oxygen concentrations.

The explosibility properties of combustible materials can be partitioned into Ignition Sensitivity and Explosion Severity. The Lower Flammable Limits [LFL], the Autoignition Temperatures [AIT], and the Minimum Ignition Energies [MIE] would be important in evaluating Ignition Sensitivity. The Maximum Explosion Pressure [Pmax] and the Deflagration Index [Kg] – a measure of burning rate – would be important in evaluating Explosion Severity. Relationships between high oxygen concentrations and the increased explosion hazards associated with these properties can be presented on a triangular/ternary graph of fuel/oxygen/inerting gas. The resulting curves closely resemble the effects of high temperature and high pressure on the flammability limits. This is a consequence of the interrelationships among AIT, MIE, Pmax, and Kg, via flame temperature [calculated], burning velocity, the Ideal Gas Law, and the Arrhenius equation.