Autoignition of combustible fluids in porous insulation materials

Conference · Thu Dec 01 00:00:00 EST 1994 · Combustion and Flame; (United States)

OSTI ID:6535982

McIntosh, A C; Bains, M; Crocombe, W; Griffiths, J F ^[1]

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1. Leeds, Univ. (United Kingdom)

The leakage of combustible fluids into the lagging of pipework in the process engineering industry can be very hazardous because of the increased residence time for oxidation as the liquid resides in the porous medium and also the substantially modified heat and mass transfer rates when compared with ignition at hot surfaces. The exothermic reaction can lead to ignition or at least severe self-heating with the consequent damage of pipework, etc. Experiments have been performed to simulate this hazard. The thermal behavior of a number of combustible liquids placed in porous material has been monitored and evidence is presented in this work that self-heating can indeed take place. It has been found that autoignition occurs at an important watershed oven temperature that is related to the volatility of the combustible fluid. A mathematical model for the autoignition of combustible liquid in an inert porous material is presented. The simple model takes a spatially uniform approach to both the energy equation and the liquid equation for the fluid and predicts a watershed temperature such that for a given concentration of fluid in the porous material, the thermal behavior of the system alters abruptly. For all practical purposes, thermal runaway is predicted beyond this watershed condition even though the classical Semenov theory simply predicts an eventual decay to a stable steady state, with no strict criticality prediction. The watershed temperature is shown to depend on volatility and reactivity.

• OSTI ID: 6535982
• Report Number(s): CONF-940711-; CODEN: CBFMAO
• Journal Information: Combustion and Flame; (United States), Vol. 99:3-4; Conference: 25. international symposium on combustion, Irvine, CA (United States), 31 Jul - 5 Aug 1994; ISSN 0010-2180
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
LIQUID FUELS
SPONTANEOUS COMBUSTION
VOLATILE MATTER
CHEMICAL ACTIVATION
COMBUSTION KINETICS
FLAMMABILITY
INDUSTRIAL PLANTS
LEAKS
MATHEMATICAL MODELS
PIPES
POROSITY
THERMAL ANALYSIS
THERMAL INSULATION
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COMBUSTION
COMBUSTION PROPERTIES
FUELS
KINETICS
MATTER
OXIDATION
REACTION KINETICS
THERMOCHEMICAL PROCESSES
400800* - Combustion
Pyrolysis
& High-Temperature Chemistry