Enclosures section determination

Step 2 Determine secondary emission plume flow rate. The plume flow rate for charging and tapping is predicted by design equations for plume flow rates (compare Section 7.5). The enclosure height is taken as the limit of plume rise. The plume rise from the open furnace before charging should also be calculated. This event is also considered as a prolonged emission. 

Extensive testing with dusts and vapors has resulted in a detailed set of empirical equations for the relief vent area (published as NFPA 68).18 The length-to-diameter ratio LID of the enclosure determines the equation(s) used for calculating the necessary vent area. For noncircular enclosures the value used for the diameter is the equivalent diameter given by D = 2VAhr, where A is the cross-sectional area normal to the longitudinal axis of the space. 

The LID ratio must first be determined for this enclosure. The longitudinal axis runs the 9 m length of the room. The cross-sectional area normal to this axis is (6 m)(6 m) = 36 m2. Thus D =... 

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