Relief and Retention Systems

The substances discharged on pressure relief must be handled in such a way that no harm to humans or environment is caused. In the first place, it must be determined if one or two-phase relief takes place. In case of doubt it is recommendable to separate the liquid phase in order to avoid further reactions. After the separation has taken place, e.g. in impingement separators or cyclones, the reaction is stopped by a large quantity of cold water containing a reaction inhibitor, if necessary. 

The safe disposal of gases and vapours must be achieved as well. Three possibilities are available the choice depends on the quantity and nature of the substances involved  

Discharge from the pressure relief system gas/liquid/two-phase  

Emission to atmo Check by calculating s Gas concentration smaller th sphere permitted tmospheric dispersion an limiting value (e.g. ERPG) 

Substances may only be released to the atmosphere if it was proved, e.g. by a dispersion calculation (vid. Sect. 10.5), that their negative impact remains within acceptable limits. Otherwise the substances have to be treated. This can be done by thermal cleanup systems, flare systems, scrubbers as well as dip-tube and other condensation units. 

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