Low pressure dryer

Patent metadata

Field	Value
Publication number	US-RE45408-E
Application number	US-47425706-A
Country	US
Kind code	E1
Filing date	Jun 22, 2006
Priority date	Sep 19, 1997
Publication date	Mar 10, 2015
Grant date	Mar 10, 2015

Abstract

A low pressure dryer for granular or powdery material includes a plurality of hoppers rotatable about a common vertical axis serially among material filling and heating, vacuum drying and material discharge positions; pneumatic piston-cylinder means for rotating the hoppers about said axis among said filling and heating, vacuum drying and discharge positions; means for heating contents of a hopper at said filling and heating positions; means for sealing a hopper at said vacuum and drying positions; means for drawing vacuum within a hopper at said vacuum drying position and means for selectably permitting downward flow of dried granular or powdery material out of a hopper at said discharge position where said hoppers move collectively and unitarily one with another.

First claim

What is claimed is

1. A low pressure dryer for granular or powdery material, comprising:
a. a plurality of hoppers rotatable about a common vertical axis serially among material filling and heating, vacuum drying and material discharge positions; b. a plurality of pneumatic piston-cylinder combinations for rotating said hoppers about said axis among said filling and heating, vacuum drying and discharge positions; c. means for heating contents of a hopper at said filling and heating position; d. means for sealing a hopper at said vacuum drying position; e. means for drawing vacuum within a hopper at said vacuum drying position; and f. means for selectably permitting downward flow of dried granular or powdery material out of a hopper at said discharge position.

2. Dryer of claim 1 further comprising:
a. a vertical shaft defining said vertical axis;
b. said pneumatic piston-cylinder combinations being equiangularly positioned about said shaft for rotating said shaft and thereby said hoppers.

3. Dryer of claim 1 wherein said hoppers are open-ended, generally vertically oriented cylindrical configuration and equiangularly positional respecting a vertical axis.

4. A hopper for use in a low pressure granular or powdery material dryer comprising:
a. a vertically-oriented cylindrical shell having open ends, adapted to be sealingly closed by selectably contacting top and bottom plates thereagainst, enabling vacuum to be drawn within said shell when said shell is at a vacuum drawing position; b. a funnel within said cylindrical shell proximate the bottom thereof; c. an internal material flow control plate located within said cylindrical shell beneath said funnel, pivotally connected to said cylindrical shell for movement about said connection away from a downwardly opening discharge orifice in said funnel to a position permitting downward granular resin material flow from said hopper.

5. Hopper of claim 4 further comprising:
a. top and bottom plates for selectively sealing said cylindrical shell allowing vacuum to be drawn therein;
b. pneumatic piston-cylinder means for urging said top and bottom plates into sealing contact with said shell; said shell being adapted to selectively dispense granular material stored therein at a dispense position removed from said vacuum drawing position.

6. A method for continuously drying granular or powdery material preparatory to mixing, molding, extruding or other processing of that material, comprising the steps of:
a. supplying granular or powdery material to a vertically-oriented cylindrical shell at a fill and heat position and heating said material within said shell by introduction of heated air into said cylinder; b. moving said vertically-oriented cylindrical shell through an arc about a vertical axis outboard of the shell periphery to a vacuum drying position and sealing open ends of said shell thereat; c. drawing a preselected level of vacuum within said sealed shell for time sufficient to evaporate moisture from said heated material to a desired degree of dryness; d. moving said shell to a discharge position at which said shell is open; e. discharging said dried material from said cylindrical shell responsively to a pneumatic piston-cylinder combination actuating a material discharge gate proximate the bottom of said shell; and f. moving said shell through an arc about said vertical axis to a fill and heat position and sequentially repeating steps (a) through (d) for so long as said granular plastic material is to be continuously dried.

7. A method for continuously supplying dried granular resin material for processing from a supply of material which is excessively moist, comprising substantially simultaneously performing the steps of:
a. heating a portion said moist material to a selected temperature at which said moisture evaporates therefrom at a preselected level of vacuum; b. drawing and maintaining said preselected level of vacuum for a second portion of said material which has been heated to said selected temperature for a time sufficient to cause said moisture to evaporate therefrom and result in said second portion of material being at a preselected dryness; and c. supplying to granular resin material processing equipment a third portion of said material which has been dried to said preselected dryness by evaporation in said preselected level of vacuum after being heated to said selected temperature.

8. The method of claim 7 wherein said portions are serially supplied.

9. A method for continuously drying granular or powdery material in batches preparatory to mixing molding, extruding or other processing of that material, comprising the steps of:
a. supplying granular or powdery material to a closeable shell at a fill position; b. heating said material within said shell by introduction of heated air thereinto; c. moving said shell to a vacuum drying position and sealing said shell thereat; d. drawing a preselected level of vacuum within said sealed shell for time sufficient to evaporate moisture from said heated material to a desired degree of dryness; e. moving said shell to a discharge position at which said shell is opened. f. discharging said dried material from said shell; and g. moving said shell to said fill position and sequentially repeating steps (a) through (f) for so long as said granular plastic material is to be continuously dried.

10. The method of claim 9 wherein said heating further comprises introducing air into said shell at a desired material temperature, measuring temperature of said air as it exists said shell, comparing said exit air temperature to said desired temperature and halting heating when said exit air reaches said desired temperature.

11. The method of claim 9 wherein said heating further comprises capturing heating air leaving said shell for recycling through said shell.

12. The method of claim 10 wherein said heating further comprises capturing heating air leaving said shell for recycling through said shell.

13. A low pressure dryer for granular or powdery material, comprising:
a. a shell movable among material filling and heating, vacuum drying and material discharge positions; b. means for moving said shell serially among said filling and heating, vacuum drying and discharge positions; c. means for heating contents of said shell at said filling and heating position; d. means for drawing vacuum within a said shell at said vacuum drying position; and e. means for selectably permitting downward flow of dried granular or powdery material out of a shell at said discharge position.

14. The dryer of claim 13 further comprising:
a. means for sealing said shell at said vacuum drying position.

15. A low pressure dryer for granular or powdery material, comprising:
a. a plurality of shells movable among material filling and heating, vacuum drying and material discharge positions; b. means for moving said shells serially simultaneously among said filling and heating, vacuum drying and discharge positions; c. means for heating contents of a shell at said filling and heating position; d. means for drawing vacuum within a shell at said vacuum drying position; and e. means for selectably permitting downward flow of dried granular or powdery material out of a shell at said discharge position.

16. The dryer of claim 15 further comprising:
a. means for sealing a shell at said vacuum drying position.

17. The dryer of claim 15 wherein said shells are collectively movable among material filling, drying and discharge positions.

18. A

Assignees

• Maguire Stephen B

Inventors

• Maguire Stephen B

Classifications

• F26B9/063

  for drying granular material in bulk, e.g. grain bins or silos with false floor (shallow layer rotary sweep drying bins F26B9/10; perforated wall silos with drying air channels in the stack F26B9/103) · CPC title

• F26B25/002

  for bulk goods · CPC title

• B29B13/065 Primary

  of powder or pellets · CPC title

• F26B5/042

  for drying articles or discrete batches of material in a continuous or semi-continuous operation, e.g. with locks or other air tight arrangements for charging/discharging · CPC title

• F26B5/04

  by evaporation or sublimation of moisture under reduced pressure, e.g. in a vacuum {(F26B11/049 and F26B17/128 take precedence)} · CPC title