Thin-film processing apparatus and method

Claim 1

In a fluid-processing apparatus of the wiped thin-film type, which apparatus comprises in combination: (a) a substantially vertical closed chamber characterized by an interior wall defining a heated surface of revolution; (b) a rotor shaft within the chamber; (c) means to rotate the rotor shaft; (d) a feed inlet at the upper part of the chamber for the introduction of feed material; (e) a product outlet remotely spaced apart and downstream from the feed inlet for removal of product material; (f) a vapor chamber within the closed chamber and upstream of the feed inlet; (g) a vapor outlet in the vapor chamber for the removal of vapor; and (h) a plurality of rotor blades secured to the rotor shaft for rotation therewith, the blades having a one end and another end, and radially and axially arranged from the rotor shaft and extending into a thin-film-forming relationship with the interior wall, said blades extending from the vicinity of the feed inlet to the vicinity of the product outlet, the peripheral edges of said blades being smooth along their length, the improvement which comprises the rotor blades characterized by a helical twist therein from the one to the other end of the blades, and the helical twist of such blades varying continuously and nonsymmetrically from one to the other end, the total helical twist of the rotor blades increasing from the feed inlet to the product outlet, up to about 180° so as to provide a maximum twist of the rotor blades at the product outlet of the apparatus, and wherein the rotor blades are substantially aligned with the rotor axis at or about the feed inlet, and wherein the degree of twist of the helical blades from the feed inlet to the product outlet increases in relationship to the film thickness of the thin film on the interior wall of the chamber, thereby providing good agitation of the thin film of material being processed, as the film decreases in thickness by evaporation, on the surface of revolution from the feed inlet to the product outlet.

Claim 7

A method of treating a fluid feed material in an evaporator apparatus which comprises a closed chamber having interior walls which define a heated surface of revolution, and a feed inlet at the one end and a product outlet at the other end, and which includes rotor blades within the chamber between the feed inlet and the product outlet, which method comprises: (a) forming a wiped film of a fluid feed material introduced into the chamber onto the interior wall of the surface of revolution by the rotation of the rotor blades, the rotor blades characterized by a nonsymmetrical helical twist extending from the one to the other end of the chamber; and (b) varying the helical twist up to about 180° of the rotor blades continuously and progressively from the one to the other end of the chamber in relationship to the film thickness on the heated surface of revolution, with the maximum twist at or about the product outlet, to provide for continuous agitation of the wiped thin film on the surface of revolution from the feed inlet to the product outlet of the chamber, while the wiped film of material moves from the inlet to the outlet and is progressively decreased in film thickness by evaporation.

Claim 8

A method of treating a fluid feed material in an evaporator apparatus which comprises a closed chamber having interior walls which define a heated surface of revolution, and a feed inlet at the one end and a product outlet at the other end, and which includes rotor blades within the chamber between the feed inlet and the product outlet, which method comprises: (a) forming a wiped film of a fluid feed material introduced into the chamber onto the interior wall of the surface of revolution by the rotation of the rotor blades, the rotor blades characterized by a nonsymmetrical helical twist extending from the one to the other end of the chamber; and (b) varying the helical twist up to about 180° of the rotor blades continuously and progressively from the one to the other end of the chamber in relationship to the film thickness on the heated surface of revolution, with the maximum twist at or about the product outlet, to provide for continuous agitation of the wiped thin film on the surface of revolution from the feed inlet to the product outlet of the chamber, while the wiped film of material moves from the inlet to the outlet and is progressively decreased in film thickness by evaporation.