Description:

Ce document est un complément à la théorie de l'ionisation de la vapeur d'eau lors d'un dopage à l'eau systeme G ou G+

Document en anglais montrant que la vapeur d'eau qui se détend se charge électriquement et ceci peut aboutir à des décharges électriques, pouvant s'averer dangereuses.

Journal of Electrostatics, 23 (1989) 69-78
Elsevier Science Publishers B.V. Amsterdam

Electrostatic Effects of Charged Steam Jets. J. FINKE. Department AA, Technical University of Magdeburg, PSF 124, Magdeburg, 3010, GOR

Summary: The electrostatic charging of wet steam during an expansion process yields a charged jet that interacts with the environment. The generation and distribution of the volume charge density in the stationary state determines the electrical field strength in the vicinity of the jet. As a consequence of drop evaporation a discharging drift current is generated. Resulting electrostatic ignition hazards and adequate safety measures are examined in
more detail in connection with the charged state of a jet.

Conclusion: The expansion of wet steam from orifices results in an electrification of the escaping jet. The charge is generated during partial disruption of the surface of water films (resulting in negative particles) and water droplets (resulting in positive particles) as the steam leaves the orifice. Little charge occurs during pipeline flow. In the constant geometric conditions of the piping and orifice the charge of the jet is only dependent on the steam content and the pressure or temperature of the wet steam. The electrical field strength in the vicinity of the jet is computable by means of the volume charge density in the stationary state. The charge density is reduced along the jet axis by
evaporating droplets forming a drift current towards earth. A relation of the type p - (c+z)-” with c,n = constants describes the decay of the charge density P along the jet axis. The ions produced form a drift current
discharging the jet. In practical cases the obtained values of the mean drift current densities are in the order of 10-lnA/cm’ at the jet boundary. Owing to the influence of the electric field and the drift current, ignition hazards and technological interference arise in the enviroment.

Prevention is possible by:
(1) earthing of neighboured conductors at all times
(2) eliminating risk from discharges from steam itself by
(a) pressure limitation or (b) specially
designed orifices or (c) ionizators.

Explication: ionisation et électrification de la détente de la vapeur d'eau à télécharger - Remarque: pour télécharger, vous devez autoriser les popups et le javascript.