Abstract: A method is disclosed of assembling a tube into two non-parallel tube sheets. The tube ends are placed in mandrels. The mandrels are moved into the holes in the tube sheets by bending the tube. The tubes are provided with convex concave curvature to provide the necessary flexibility to aid assembly.

Abstract: A heat exchanger including a plurality of tubes arranged in at least three side-by-side planes, the tubes being held at their ends in the sidewalls of an even-sided polygon of at least six sidewalls, each sidewall being connected to its opposite sidewall by tubes in at least one of the planes.

Abstract: Separating volatile impurities from AlCl.sub.3 by supplying impure AlCl.sub.3 into a molten salt bath of a gas separation compartment in an electrolysis cell. The impurities are removed from the compartment and molten salt bath containing dissolved AlCl.sub.3 is carried under a partition into a chamber where the AlCl.sub.3 is electrolyzed. In a preferred embodiment, desublimation is avoided by supplying AlCl.sub.3 to the bath as a gas rather than in solid form.

Abstract: Fluidizable particulate solids are removed from a first zone operating at a relatively higher temperature and pressure to a second zone or collector operating or maintained at a lower temperature and pressure by an improved drain or particle removal system. The improved system includes moving the particles from the first zone downwardly within a substantially vertical inlet conduit or leg into the lower regions of a first chamber and upwardly through that chamber under fluidized particle transport conditions energized by a fluidizing media provided in the chamber. The particles move to a second chamber by overflowing a weir separating the first and second chambers and are mixed with cooler particles which extract heat within the second chamber under fluidized particle transport conditions energized by a second fluidizing gas source which further transports the particles to the collector or second zone. Heat is removed from the second chamber by indirect heat exchange.

Abstract: A method including producing metal by electrolysis in a molten salt bath, in a bipolar cell, with the improvement involving electrically isolating the bath with a continuous, electrically insulating material in the portion of the cell containing the bath, the material being a plastic or rubber.

Abstract: A method for producing metal by electrolysis in a molten salt bath containing superimposed electrodes, at least one of which is a bipolar electrode. The arrangement of the electrodes creates interelectrode spaces between them. Bath is swept through these interelectrode spaces. This method is improved by providing circulation of the bath from one interelectrode space to the next at a location inwards of the outer peripheries of the electrodes. This can be accomplished e.g. by boring holes through the electrodes. It can also be accomplished by breaking the electrodes into individual, mutually separated stacks of electrodes, the circulation of the improvement then occurring e.g. in the space between the stacks.

Abstract: A method is disclosed by which heat may be extracted from an electrolysis chamber containing a molten salt bath. The method includes providing the chamber with a portion having a surface bordering directly on a gas space above the molten salt bath. Constituents from the bath are spewed and/or evaporated into this gas space. The mentioned portion is cooled so that the temperature of the surface bordering on the gas space is at least 200.degree. C below the bath temperature and above the freezing point of the mentioned constituents. This allows the constituents to deposit on the mentioned portion in liquid form, and drop back into the bath.