Construction and arrangement of wipers in thin-film evaporators

Claim 1

A THIN-FILM EVAPORATOR APPARATUS COMPRISING A DRUM MEANS, AND A PLURALITY OF VANE MEANS DISPOSED WITHIN SAID DRUM MEANS AND MOUNTED FOR ROTATION THEREWITHIN, SAID DRUM MEANS HAVING AN INNER WALL EVAPORATOR SURFACE ADAPTED FOR MAINTAINING A THIN FILM OF LIQUID TO BE EVAPORATED THEREON, SAID VANE MEANS BEING AXIALLY DISPOSED IN SAID DRUM MEANS IN SLIDING ABUTMENT WITH SAID EVAPORATOR SURFACE ALONG A PORTION OF THEIR RADIALLY OUTERMOST EDGES AND IN CLOSELY OVERLAPPING SPACED RELATION TO ONE ANOTHER AT AN ANGLE WITH RESPECT TO THE PLANE OF THE RADIUS OF THE DRUM AT ANY POINT TO FORM AN OVERLAPPING VANE ARRANGEMENT ANNULAR IN CROSS-SECTION CIRCUMFERENTIALLY CLOSING OFF DIRECT RADIAL COMMUNICATION BETWEEN THE DRUM AXIS AND SAID EVAPORATOR SURFACE, WHEREBY WITH RESPECT TO SAID EVAPORATOR SURFACE SAID VANE MEANS ARE POSITIONED SUCH THAT ANY LINE PASSING RADIALLY FROM THE AXIS OF SAID DRUM MEANS TO SAID EVAPORATOR SURFACE INTERSECTS AT LEAST ONE VANE MEANS.