Hi mate, and welcome to subsim!
You could do a search over at the SHIII mods forum, or just use the original smoke from vanilla SHIII.
(The files are locate in the folder SHIII/data/Textures/TNormal/tex, and named smoke_volum.tga and smoke_volume02.tga, if i am not mistaken..... Please correct me if im wrong on this, mates!!!)
Edit: Read Kpt. Lehmanns post further down. He knows this to the bone, mate, believe me!