Fire and Explosion Hazard during Depressurization of Equipment with Ammonia

The statistics of fires and explosions of ammonia in the sphere of its circulation (production, storage, use) indicate the relevance of studies aimed at preventing emergency situations, localization, and elimination of accidents consequences. Equally important are studies on the development of assessments of accidents consequences associated with the release and spillage of ammonia from the equipment in various aggregate state. When ammonia is released, the resulting mixture of the product with air can vary in density from the formation of gas-air clouds with a density below the air density to buoyancy and excess air density, depending on the release conditions (pressure and temperature in the equipment; the sizes of the hole through which ammonia enters the surrounding space; the location of the hole in the equipment (gas or liquid phase). When the liquid ammonia leaks out, the spills are formed, from the surface of which the product evaporates especially rapidly in the first moments after the spill. Based on the computational and analytical studies, the design schemes and formulas were proposed for determining the parameters of the explosion: excess pressure and impulse of the undisturbed (incident) and reflected from the obstacles of the blast wave, as well as the nature of the destruction depending on the distance from the epicenter of the explosion, caused by the depressurization of equipment with ammonia. An accident scenario is considered, according to which the ammonia with a mass of 100 kg, when depressurizing, breaks out from the equipment of an industrial refrigerator. Ammonia vapors mix with the air to form a cloud that ignites and explodes. As an example, the overpressure and impulse during explosion of ammonia at a distance of 30 m from the epicenter of the explosion were determined. According to the empirical formula for estimating the distances from the epicenter of the explosion to a given place, the levels of the consequences of building destruction (complete, medium, small, moderate damage) can be established.