GB480816A - Improvements in vacuum driers - Google Patents

Abstract

480,816. Rotary conveyers. INTERNATIONAL PATENTS DEVELOPMENT CO. Dec. 15, 1936, No. 34466. Convention date, Feb. 6. [Class 78 (i)] [Also in Group XIII] Apparatus for drying pulverulent and adhesive materials comprises a chamber connected to an evacuating system and provided with superposed drying tables with heated bottom surfaces, cage roller structures supported by the tables and adapted to disintegrate lumps of material, and scrapers movable to transfer the material downwardly from table to table, through openings arranged alternately at the circumference of a table and at the centre of a table. In the construction shown, used for the drying of starch, chamber 10 connected to an evacuator 11 is provided with hollow tables 13, 14 communicating with a steam supply pipe 37. The tables are connected to a shaft 19 which is adapted to be rotated by means of an electric motor 48. The shaft carries radial arms 53 provided with scrapers 17 which are adapted to move the starch over the tables. The starch is discharged over the outer edges of the tables 13 on to the tables 14 on which it is moved inwardly for discharge through central openings 20. It is finally received by a table 13 from which it is discharged through rotating valve 12a. This valve is of the same construction as a valve 12 through which the starch is fed into the chamber 10. Each of the tables is divided underneath into a number of passages by concentric ribs 28. The passages communicate with a common inlet passage 35 connected by a pipe 36 to the supply pipe 37. Water of condensation is discharged from the passages through separate ports 38 .. 41 communicating with steam traps 42. The arms 53 are connected by resilient strips 75 to frames carrying rollers 18 adapted to break up lumps of starch. Each roller comprises several twisted bars 69 rotatably mounted in end discs 62, which are rotatably mounted in a frame 70. The rotary valve for the supply of starch comprises a rotary member 89 provided with pockets 83 adapted to register with an inlet passage 84 and with an outlet passage 85. An air inlet valve 96 is normally opened and permits atmospheric air to blow starch from pocket 83 through the passage 85 into the evacuated chamber 10. As the rotary valve rotates each pocket 83 becomes evacuated before registering with the inlet passage 84 supplying starch so that the vacuum ensures that the pocket 83 is completely filled. The rotary exhaust valve is connected to the pipe 21 leading to the evacuator and the air valve 96 is closed so that each pocket 83 is evacuated before it receives the discharged starch.