Method and a drum coater for coating small items, such as tablets, and a coating system comprising such drum coaters

A drum coater comprising:

• a substantially cylindrical drum (11) having a peripheral drum wall (12) and a predefined diameter, said drum having a substantially horizontal axis of rotation (17), a top section (20) and a bottom section (21) being defined above and below, respectively, the axis of rotation, said drum (11) being adapted to contain tablets,
• a coating zone,
• one or more spray nozzles (26) directed towards the coating zone and configured to implement a spray coating of spraying a coating in a direction towards the coating zone and onto a cascade of the tablets in the coating zone, and
• driving means,
• wherein
• the driving means is adapted to set the drum (11) to spin at a rotational speed such that the tablets are pressed towards the periphery of the drum (11) by the centrifugal force and the tablets are held against the peripheral drum wall (12) producing, while the spray coating is implemented by the one or more spray nozzles (26) spraying the coating in the direction towards the coating zone and onto the cascade of the tablets in the coating zone, a substantially annular bed of the tablets extending around the axis of rotation, the substantially annular bed of the tablets being at least at an inner portion of the drum (11) that is opposite to the direction in which the one or more spray nozzles (26) are directed to spray the coating towards the coating zone and the cascade of the tablets in the coating zone, and that
• cascade creating means are provided by loosening means configured to form the cascade of the tablets that is mostly in the top section (20) of the drum and extends from a first quadrant of the drum to a second quadrant of the drum, the first quadrant and the second quadrant both being in the top section (20) of the drum,
• wherein the drum coater further comprises a deflecting nozzle, arranged at the top section of the drum, configured to provide, as an air knife of the loosening means, a stream of air or gas towards the tablets through the deflecting nozzle and into the top section of the drum.