Effects of dust exposure on the environment of pressure-discharging parts of plants

Status:

completed 12/1994

Aims:

The pressure-discharge of dust explosions in containers leads to pressure and flammable reactions in outer areas which can cause damage to persons and equipment. Available research results enable estimations of safety distances to be made by means of empirical equations, which were incorporated in VDI guideline 3673. The corresponding tests could only be carried out with corn starch due to costs. They demonstrated, however, that the reaction in outlying areas also depended strongly on specific material characteristics. Goal: determining the influence of specific material characteristics of dust/silo products on the required safety distances to blow-off openings in accordance with VDI-guideline 3673.

Activities/Methods:

Examining the influence of the specific material characteristic qualities of dust cloud formation parameters (concentration, turbulence and velocity distribution as a function of time) and the time intervals between pressure discharge, dust cloud formation and free jet ignition; experiments to alter the external effect of dust explosions by dividing the discharge area into several independent sections

Results:

In the case of the smallest Kst-value (hard coal: 100 bar m/s) the calculated safety distances are too large; in the case of the highest Kst-value (aluminium: 300 bar m/s) a safety factor is necessary. The external effect is reduced by enlarging and sub-dividing the discharge area.

Publications:

Schumann, St.; Rastogi, A.K.: Dust Explosion Venting Experiments and Numerical Modelling. 8th International Symposium on Loss Prevention and Safety Promotion in the Process Industries, Antwerpen/Belgium, 6/95

Schumann, St.; Rastogi, A.K.; Friehmelt, V.: Auswirkungen von Staubexplosionen auf die Umgebung druckentlasteter Anlagenteile. DECHEMA-Jahrestagung, Wiesbaden 5/95 CREDIT Projekt Video: Der Schutz der Umwelt vor Staubexplosionen

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