THE POTENTIAL OF SUFFICIENT STATIC ELECTRICITY FOR IGNITION DURING TANKER WASHING

Waste-derived fuel is an environmentally friendly method for destroyin g waste and recovering the energy value it contains. The fuel is chara cterized as a mixture of various solvents with a flashpoint in the fla mmable range. In addition to these solvents, the waste fuel contains s olid material. During the transfer of this material to storage tanks, some of the solid material is left behind in the tankers and rail cars . The ideal solution to remove this solid material is to wash the tank vehicle with the same waste fuel. With the waste fuel being in the fl ammable range, there is a concern about the washing operation causing ignition due to static electricity. Scaled experiments were conducted to assess the potential for static electricity to cause ignition. Alth ough several ignition mechanisms were assessed, this paper is concerne d with the charged mist caused by the high velocity solvent jet imping ing on the tank wall. Isopropyl alcohol, mixed xylenes, and mineral sp irits were evaluated. An aerosol electrometer was used to measure char ge per unit volume of mist sampled. Discharge generation was assessed using an analytical model which estimates electric field corresponding to measured charge density for various configurations.