Heating of tank car walls for ejecting frozen or congealed cargo

Abstract

A device and method for unloading frozen or congealed crude oil, oil product, or chemical cargo from a railway or highway tank car. A brief heating step uses the high thermal conductivity of metal tank walls, and the low thermal conductivity of oil or chemical cargos, to thaw a relatively thin band of cargo adjacent to the longitudinal tank wall. This thin band of thawed liquid lubricates the remainder of the plug, which remains solid, so that the plug can be mechanically ejected into a receiving trough positioned at the same height as the emerging plug; this avoids the requirement of completely thawing the frozen cargo before it can be pumped out. A tank car is disclosed having at least one end wall that can be opened, allowing a frozen or congealed mass to be physically ejected from the tank as a solidified plug. The ejection mechanism can involve pneumatic or hydraulic pressure which moves an interior wall along the length of the cylinder, or a large piston-type movable wall coupled to one or more driving rods. The brief heating step uses heating belts wrapped around the tank, passage of steam or hot water through a space between two cylindrical walls in a double-walled tank, or a crane-supported device which can be lowered over a tank. After ejection, the plug can be thawed, sliced, or otherwise prepared for burning, refining, repackaging, or any other use. The heating devices can be used in conjunction with conventional internal steam coils, or with tank cars having rusted or broken steam coils, to speed up a conventional thawing operation.

Dependencies are inferred from the claim text.