Emission from Leaks

The released fluid may be a gas or a vapour, a liquid, a two-phase mixture, a mixture of several components or a fluid in supercritical state (vid. Example 10.19). If the release is from a vessel storing a liquefied gas, liquid is released if the leak is below the liquid level. If the leak is above the level either vapour or a mixture of liquid and vapour is released. For a given difference of pressures across the leak usually higher mass flow rates are reached if a liquid or liquid/vapour mixture is released than in case of a gas or vapour. The equipment from which the release takes place can be a vessel or a heat exchanger, a pump or a pipe. The maximum released quantity depends on the material inventory and the possibility of isolating the leak. The size of the leak may vary between a large portion of the vessel surface and a limited aperture as that of a hole. 

The mass flow rate from a rounded nozzle branch is greater than through a conventional pipe branch but it is the latter which is generally used. Further possibilities are leaks from drain and sample points, pressure relief devices, bursting discs, seals and flanges, and pipe ends. 

Releases may take place inside buildings or outdoors. This influences the dispersion behaviour. Outdoor releases often remain without grave consequences because of quick dilution of the released materials. A release of the same quantity indoors, however, may have grave consequences because of toxic impacts and the possibility of mixtures with air within the hmits of flammability. The elevation of the point of release also influences the dispersion behaviour. A release of a liquid below ground level may remain completely contained. On the other hand, a release of a gas or vapour above ground may lead to a large-scale dispersion. 

Furthermore dispersion is influenced by the initial momentum of the released fluid. Gas or vapours released with low initial momentum lead to plume formation. If the initial momentum is high, turbulent jets result. Releases of liquids produce a stream with low initial momentum and a liquid jet, if the momenrnm is high. In both cases eventually a pool is formed. 

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Emissions from leaks from gasoline terminals, gasoline dispensing facilities, and petroleum refinery sources... 

Emission from leaks from gasoline tank trucks and vapor collection systems Organic emissions VOC emissions from petroleum... 

SPILL CLEAN-UP use engineering controls and work practices as soon as possible clean coke oven doors before each charge to make sure there is a metal-to-metal fit during coking to prevent emissions from leaking out cut off gas supply by purging pipes with steam or an inert gas. 

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