Flame-arrestor effect

The whole set-up for partial oxidation comprises a micro mixer for safe handling of explosive mixtures downstream (flame-arrestor effect), a micro heat exchanger for pre-heating reactant gases, the pressure vessel with the monolith reactor, a double-pipe heat exchanger for product gas cooling and a pneumatic pressure control valve to allow operation at elevated pressure [3]. 

In the past it was difficult to prevent the spread of explosions through vent systems, as flame arrestors were effective only when located at the ends of pipes. Effective inline detonation arrestors are now availabe. Like all flame arrestors they will, of course, need regular cleaning, something that is often neglected. In other cases, when tanks have been over-... 

A special study [74] was commissioned by the American Petroleum Institute (API) entitled Mitigation of Explosion Hazards of Marine Vapor Control Systems. The report examines the effects of deflagradons and detonations in pipes in the region of detonation flame arrestors. The primary objective was to resolve potential... 

Research has shown that pressure-vacuum vents are just as effective as flame arrestors for storage tanks against internal ignitions. 

Air is removed from the system by vent lines connected to all vessels likely to contain some incoming air the extractor, the desolventizer, etc. A slight vacuum, induced by a vent fan, draws noncondensibles from all the condensers and vented vessels into a common header where they pass through a water-cooled vent condenser followed by some device to remove as much solvent vapors as practical and then pass through a flame arrestor before being released to the atmosphere. The simplest, least expensive device is a refrigerated condenser to lower the effluent air temperature. The air leaves the system saturated with solvent vapor the lower the temperature, the less solvent in the air. A more effective method removes the solvent from the air by either absorption or by extraction. 

The combustion process is initiated by an ignition source converting some number of methane molecules into free radicals. Free radicals are in turn converted to OH free radical. Possible oxygenated compounds include aldehyde, alcohol, carboxylic acid, and oxide. The hydroxyl free radical then reacts with methane and is regenerated. The successive (chain type) combustion reaction is impeded by destruction of the OH radicals. Solid surfaces often destroy the OH radicals before they can react with hydrocarbons. The same effect is exploited in a porous-bed flame arrestor. In general, the combustion rates are very fast and nearly measurable with a few exceptional situations where time scales can be expanded to microseconds (KT6 s). The... 

Vapor cloud explosions are due to rapid combustion of flammable gas, mist, or small particles that generate pressure effects due to confinement they can occur inside process equipment or pipes, buildings, and other contained areas. A vapor cloud explosion can be either a deflagration or a detonation (the distinction between deflagrations and detonations is important when deciding on whether or not to use a flame arrestor in pressure relief systems). 

This is frequently the most expensive, inconvenient and least effective means of preventing fires. Flame-proof lighting, spark-proof switches and flame-arrestor devices, etc., may be appropriate where large volumes of highly flammable materials are stored or used, but the scale of most museum workplace activities probably does not justify such preventive measures. 

Flame (flash) arrestor n. Devices utilized on vents for flammable liquid or gas tanks, storage containers, cans, gas hnes or flammable hquid pipelines to prevent flashback (movement of flame) through the line or into the container, when a flammable of explosive mixture is ignited. Wire screen of 40 meshes is utflized on smaller openings. On larger openings, parallel metal plates or tubes are more effective. 

---