Fluidized bed coating apparatus

Patent metadata

Field	Value
Publication number	US-10071390-B2
Application number	US-201314435317-A
Country	US
Kind code	B2
Filing date	Oct 10, 2013
Priority date	Oct 12, 2012
Publication date	Sep 11, 2018
Grant date	Sep 11, 2018

Abstract

A fluidized bed coating apparatus for coating liquid onto the surfaces of particles directed into a coating chamber. A liquid spray nozzle assembly disposed below a hollow separator within the coating chamber includes an ultrasonic atomizer for atomizing coating liquid into a fine liquid particle cloud and a pressurized air directing air cap for forming the ultrasonically atomized fine liquid particle cloud into a cone shaped spray pattern and propelling the liquid particles through the separator into an upbed region of the coating chamber for recirculation in an outbed region, and through the separator. A cooling air passageway system is provided within the spray nozzle assembly for cooing the ultrasonic atomizer during operation.

First claim

The invention claimed is:

1. A fluidized bed coating apparatus for coating liquid onto surfaces of particles comprising:
a vessel that defines a coating chamber for receiving particles to be coated;
said vessel having a processing air inlet for connection to a processing air supply for communicating processing air into an underside of said coating chamber;
a filter on an upper side of said coating chamber;
a coating liquid spray nozzle projecting upwardly toward said coating chamber from an underside thereof for spraying coating liquid upwardly into said coating chamber;
a hollow separator disposed in upstanding relation relative to a discharge end of said coating liquid spray nozzle into which a coating liquid sprayed from said coating liquid spray nozzle is directed;
said processing air inlet being operable for directing an upward processing air flow such that the particles to be coated are circulated upwardly through said separator to an upbed region of said coating chamber and then downwardly through a downbed region of the coating chamber outwardly of said separator for return into and through said separator;
said coating liquid spray nozzle including an elongated housing, said elongated housing having a coating liquid supply passage extending through the housing with an upstream end coating fluid inlet for connection to a coating liquid supply;
said coating liquid spray nozzle including an ultrasonic atomizer having an ultrasonic driver and a cannular atomizing stem supported adjacent a downstream end of said elongated housing, said cannular atomizing stem terminating in an atomizing surface and having a coating liquid flow passage extending along an axis of the stem communicating with said elongated housing liquid supply passage for directing coating liquid to said atomizing surface, said ultrasonic driver being electrically activatable to vibrate said atomizing surface for atomizing coating liquid directed onto the atomizing surface into a fine liquid particle cloud proximate the atomizing surface;
said elongated housing having a forming air passage with an upstream forming air inlet end for connection to a forming air supply, an air cap mounted at a downstream end of said elongated housing defining an air chamber about said atomizing stem in fluid communication with said forming air passage, said air cap and atomizing stem defining a forming air discharge orifice communicating with said air chamber from which an air stream is emitted for forming the cloud of fine ultrasonically atomized liquid particles into a well-defined and controlled pattern short of the filter and without clogging the filter for optimum interaction and coating of particles in the upbed region of the coating chamber; and
said coating liquid spray nozzle having an annular cavity surrounding said ultrasonic driver, said elongated nozzle housing having a cooling air passageway with an upstream cooling air inlet for coupling to a cooling air supply and for directing cooling air to said annular cavity for cooling said ultrasonic driver during operation of said coating liquid spray nozzle.

2. The fluidized bed coating apparatus of claim 1 including a processing air plenum disposed on an underside of said vessel for coupling to said processing air supply and for supplying processing air to said processing air inlet, said elongated nozzle housing extending through said air plenum with said forming air inlet, coating fluid inlet, and cooling air inlet being disposed outside said air plenum.

3. The fluidized bed coating apparatus of claim 2 in which said coating liquid spray nozzle has an inlet body disposed below and exterior to said air plenum, said forming air inlet, coating liquid inlet, and cooling air inlet communicate with said inlet body.

4. The fluidized bed coating apparatus of claim 1 in which said air cap is configured for directing pressurized air into said coating chamber in a rotary swirling direction for forming the ultrasonically atomized fine liquid particle cloud into a cone shaped spray pattern and propelling the liquid particles though said separator.

5. The fluidized bed coating apparatus of claim 1 including an orifice plate disposed between said processing air inlet and a lower end of said coating chamber, said orifice plate being formed with an inner array of orifices for communicating a relatively high volume of processing air upwardly through said separator and a second array of orifices outwardly of said separator for directing a relatively lower pressure air flow about an outer perimeter of said separator.

6. The fluidized bed coating apparatus of claim 5 in which the orifices of said inner array are sized larger than the orifices of said second array.

7. The fluidized bed coating apparatus of claim 5 in which said coating liquid spray nozzle is positioned in aligned relation to a central opening in said orifice plate with said air cap projecting outwardly of said central opening.

8. The fluidized bed coating apparatus of claim 7 in which said air cap has a frustoconical end protruding through said central opening.

9. The fluidized bed coating apparatus of claim 5 in which said orifice plate includes a third outermost annular array of orifices larger in size than the orifices of said second array for directing an outer annular air flow into said coating chamber for preventing accumulation of coated particles on a side wall of said vessel.

10. The fluidized bed coating apparatus of claim 1 in which said elongated nozzle housing includes a return air passage communicating with said annular cavity for communicating air from said annular cavity to an outlet port.

Assignees

• Spraying Systems Co

Inventors

• Filicicchia Daniel J
• Huffman David C
• Smith Brian K
• Szczap Joseph P

Classifications

• B01J2/18

  using a vibrating apparatus · CPC title

• B01J2/16

  by suspending the powder material in a gas, e.g. in fluidised beds or as a falling curtain · CPC title

• B05B17/0646 Primary

  Vibrating plates, i.e. plates being directly subjected to the vibrations, e.g. having a piezoelectric transducer attached thereto · CPC title

• B05B7/066

  with an inner liquid outlet surrounded by at least one annular gas outlet · CPC title

• B05B17/063

  having an internal channel for supplying the liquid or other fluent material · CPC title