Continuous fluidization-type powder drying plant and method of use

Claim 1

A continuous fluidization-type powder drying plant for drying high density chemical powders comprising in combination: a. at least first and second adjacent vertical drying columns (I, II) disposed in series at substantially the same height and the same horizontal level separated by a common wall, porous plates (1, 1'') towards the bottom of said columns with gaps above said plates providing communication between said columns, the first drying column being substantially laRger than the second drying column; b. a moist powder feeder (2) on the upper portion of said first drying column and at least one dried powder outlet (4) on the lower portion of the last column, at least one heat exchange device (6) in one of said columns, heated drying communication chambers (5'', 5'''') at the undersides of said columns, fine powder mixed gas outlet pipes (7'', 7'''') coupled to a cyclone collector (8) leading from the upper portion of said columns, including a throttle valve in said second drying column outlet pipe (7''''), a separate gas discharge line from said cyclone collector; c. a gas cleaning and dehumidifying column (9) fed by said gas discharge line towards the bottom of said dehumidifying column, a hexane cooling liquid spray means at the top of said dehumidifying column, a hexane cooler (9'') next to said column including pump means (15) to circulate the hexane from the bottom of said dehumidifying column (9) through said cooler (9'') to the spray means at the top of said dehumidifying column, an outlet line from the top of said dehumidifying column over said spray means; and, d. first and second branch lines from said outlet line, said first branch line going to said first drying column communication chamber (5''), said second branch line going to said second drying column communication chamber (5''''), a first pump (14), a gas cooler (11) and heater (12) in said first branch line, a second pump (13) and steam heater (10) in said second branch line, whereby said first drying column is supplied under pressure with a gas of relatively high humidity and said second drying column with a gas of relatively low humidity.

Claim 4

The method of fluidized drying of chemical powder material so that heated drying gas is separated into a gas of high humidity and a gas of low humidity and treating said gases in individual circuits, circulating a greater part of the heated gas at a relatively high temperature and finish drying the material by cooling and drying a small quantity of circulating gas at a low temperature, comprising the steps of: a. passing the powder raw material through a dehumidifier towards the top of a first larger vertical elongated treating zone communicating with a parallel second similar smaller treating zone; b. withdrawing said treated material from the top of said zones into a cyclone collector, while withdrawing material from powder outlets in the bottom of said second treating zone; c. leading out drying gas from the top of said cyclone collector to the bottom of a circulating cleaning and dehumidifying zone, removing the drying gas from the top of said cleaning and dehumidifying zone; and d. separately feeding said cleaned and dehumidifying drying gas through first and second branch lines to the bottom of said first and second vertical treating zones while subjecting said treating gas in said branch lines to selected cooling, heating and steam heat applications so as to selectively supply said first and second vertical treating zones at the bottom thereof with drying gas of high humidity in said first treating zone and of low humidity in said second zone.

Claim 5

The method of fluidized drying of chemical powder material so that heated drying gas is separated into a gas of high humidity and a gas of low humidity and treating said gases in individual circuits, circulating a greater part of the heated gas at a relatively high temperature and finish drying the material by cooling and drying a small quantity of circulating gas at a low temperature, comprising the steps of: a. passing the powder raw material through a dehumidifier towards the top of a first larger vertical elongated treating zone communicating with a parallel second similar smaller treating zone; b. withdrawing said treated material from the top of said zones into a cyclone collector, while withdrawing material from powder outlets in the bottom of said second treating zone; c. leading out drying gas from the top of said cyclone collector to the bottom of a circulating cleaning and dehumidifying zone, removing the drying gas from the top of said cleaning and dehumidifying zone; and d. separately feeding said cleaned and dehumidifying drying gas through first and second branch lines to the bottom of said first and second vertical treating zones while subjecting said treating gas in said branch lines to selected cooling, heating and steam heat applications so as to selectively supply said first and second vertical treating zones at the bottom thereof with drying gas of high humidity in said first treating zone and of low humidity in said second zone.