초록 ▼

A self-cleaning centrifugal dryer system and method for removing surface moisture allow complete removal of plastic pellets, flakes and particles from the dryer and water-conveying or water processing system during or after each drying cycle. By eliminating plastic particulate retention in the dryer

A self-cleaning centrifugal dryer system and method for removing surface moisture allow complete removal of plastic pellets, flakes and particles from the dryer and water-conveying or water processing system during or after each drying cycle. By eliminating plastic particulate retention in the dryer and throughout the water conveyance and processing systems whereby contamination of different type materials dried during a subsequent drying cycle is avoided. Air and water alone or in combination under pressure are discharged toward various accumulation or occlusion ("hang-up") points in the dryer and throughout the water-conveying or processing system to remove retained plastic pellets, flakes and particles.

대표청구항 ▼

What is claimed is: 1. A self-cleaning centrifugal dryer system for removing surface moisture from pelletized product in the form of a slurry of pellets and water and removing particulates from the dryer system after each drying cycle comprising an agglomerate catcher having an agglomerate catcher

What is claimed is: 1. A self-cleaning centrifugal dryer system for removing surface moisture from pelletized product in the form of a slurry of pellets and water and removing particulates from the dryer system after each drying cycle comprising an agglomerate catcher having an agglomerate catcher grate, a dewaterer having at least one dewatering screen and a centrifugal pellet dryer having a housing, a screen mounted within said housing in spaced relation to the housing, a pellet lifting rotor positioned within said screen, a motor drivingly connected to said rotor, and fluid pressure spray nozzles positioned interiorly of said housing for discharging pressurized fluid toward said agglomerate catcher grate, said dewatering screen and said dryer screen, rotor and housing for removing particulates from said dryer system to eliminate contamination of material being dried in a subsequent drying cycle. 2. The dryer system as claimed in claim 1, wherein said spray nozzle assembly includes nozzles spaced circumferentially around the screen and in radially spaced relation to the interior of the housing and the exterior of said screen for cleaning the surfaces of the screen and housing. 3. The dryer system as claimed in claim 2, wherein said spray nozzles are positioned in staggered vertical position in relation to said screen and housing to clean all surfaces of the screen and housing. 4. The dryer system as claimed in claim 1, wherein said rotor includes a hollow shaft positioned in an elongated vertical hollow body, said hollow shaft including a rotary connection to a source of pressurized fluid said hollow shaft including passages communicating the hollow shaft with the interior of the hollow body of the rotor, said rotor including a bottom having apertures therein for discharging pressurized fluid into a lower section of said housing for dislodging pellets and plastic particles and flakes from said lower section of said housing. 5. The dryer system as claimed in claim 1, wherein said slurry inlet is positioned at a lower end of said housing, said dried pellet outlet is positioned at an upper end of said housing, and said motor is mounted on said upper end of said housing. 6. The dryer system as claimed in claim 1, wherein an agglomerate catcher is positioned in advance of said slurry inlet for removing pellet agglomerates from said slurry before entering said slurry inlet. 7. The dryer system as claimed in claim 1, wherein a pellet dewaterer is positioned in advance of said slurry inlet to remove bulk water from said pellet and water slurry before said pellets enter said slurry inlet. 8. The dryer system as claimed in claim 1, wherein said dried pellet outlet includes a discharge chute and a diverter valve in said chute to enable the discharge of dried pellets to selected discharge openings. 9. The dryer system as claimed in claim 6, further comprising a cleaning spray nozzle associated with said agglomerate catcher for directing pressurized fluid against an agglomerate screen to clean agglomerates from said screen for discharge from said agglomerate catcher. 10. The dryer system as claimed in claim 8, further comprising a cleaning spray nozzle associated with said discharge chute for directing high pressure fluid to dislodge pellets, plastic particles and flakes from said diverter valve and to clean said dried pellet outlet and said upper end of said housing and rotor. 11. The dryer system as claimed in claim 1, further comprising an underwater pelletizer and a slurry pipe circuit associated with said dryer, including a water box bypass pipe provided with a high pressure fluid nozzle for injecting high pressure fluid into said bypass pipe to clean said bypass pipe and cause a high pressure water surge into said dryer. 12. A method of self-cleaning a centrifugal pellet dryer system including an agglomerate catcher having an agglomerate catcher grate, a dewaterer having at least one dewatering screen and a centrifugal dryer having a housing, a screen mounted within said housing in spaced relation to the housing, a pellet-lifting rotor positioned within said screen, and a motor drivingly connected to said rotor, in which dried particulates become lodged in hang-up points in said agglomerate catcher, dewaterer, and dryer, said method comprising the steps of directing high pressure fluids in a timed sequence from spray nozzles selectively positioned inside said agglomerate catcher, said dewaterer, and said dryer toward said hang-up points. 13. The method as claimed in claim 12, wherein said high pressure fluids includes water flowing at a rate of at least 40 gpm. 14. The method as claimed in claim 12, wherein said high pressure fluids includes air at a pressure of at least 60 psi. 15. A method of self-cleaning a centrifugal pellet dryer having a housing, a screen mounted within said housing in spaced relation to the housing, a pellet-lifting rotor positioned within said screen, and a motor drivingly connected to said rotor, in which dried pellets become lodged in hang-up points in said dryer, comprising directing high pressure fluids in a timed sequence from nozzles selectively mounted between an interior of said housing and an exterior of said screen toward said hang-up points. 16. The method as claimed in claim 12, wherein said dryer system includes a water box bypass line having at least one valve for operation thereof, and said method further comprising the step of injecting high pressure gas into said bypass line to purge particulates from hang-up points therein. 17. The dryer system of claim 1, further comprising a water box bypass line having at least one valve for operation thereof, and a gas inlet to inject pressurized gas to purge particulates from hang-up points in said bypass line. 18. The method as claimed in claim 16, wherein said gas is air. 19. The method as claimed in claim 12, wherein said high pressure fluids include water flowing at a rate of between about 80 gpm and about 100 gpm.