Drying and gas or vapor contact with solids – Apparatus – With apparatus using centrifugal force
Reexamination Certificate
1998-10-19
2001-05-29
Bennett, Henry (Department: 3744)
Drying and gas or vapor contact with solids
Apparatus
With apparatus using centrifugal force
C034S173000, C034S182000, C034S183000
Reexamination Certificate
active
06237244
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a centrifugal dryer for removing surface moisture from pellets of resin material having a diameter generally ranging between approximately 0.015 to approximately 0.25 inches received from an underwater pelletizer. More specifically, the present invention relates to a dryer which is constructed with smaller dimensions enabling it to effectively operate at low volume rates and be easily assembled and disassembled to facilitate cleaning and replacement or interchange of components with its overall size enabling it to be effectively used in small applications, especially laboratory applications.
2. Description of the Prior Art
Centrifugal pellet dryers are well known and have been successfully used for many years to separate water from a water and pellet slurry and remove surface moisture from the pellets in order to provide relatively dry surfaces on the pellets for subsequent use. Previously known centrifugal pellet dryers are used for the purpose of removing surface moisture from pelletized products and are usually a relatively large machine for producing a large volume of dried pellets. The following U.S. patents relate to centrifugal pellet dryers:
4,476,019
5,187,880
5,611,150
4,570,359
5,505,537
The centrifugal pellet dryers disclosed in the above prior patents are primarily used in high volume production of dried pellets and are not practical for operation at low rates of production and are not sized to use in a laboratory application or other small operations.
Accordingly, the present invention seeks to overcome this deficiency in the prior centrifugal pellet drying constructions by incorporating unique features not shown in the prior art. For example, the pellet dryers of the prior art do not have a sectional housing with the sections being connected together by bolted external flanges for easy separation and access to the internal components. The above patents also fail to disclose a centrifugal pellet dryer having a base section attached directly to a tank for receiving the water from the water and pellet slurry thereby eliminating the necessity of using piping systems to drain water from the dryer. In addition, the prior art does not disclose a centrifugal pellet dryer in which the rotor is supported from a single upper bearing with the lower end of the rotor being rotably guided by an alignment bushing which is self lubricating and is cooled by the water of the water and pellet slurry thereby eliminating the need for providing a sealed bearing or other special device to protect a bottom bearing from the water. Still another feature not shown in the prior art is the use of a cylindrical screen in a centrifugal pellet dryer which telescopically engages a recessed edge of cup-shaped support members at the top and bottom ends of the screen and is supported by a pair of holding clips in the form of hooks to engage supporting pins on the upper cup-shaped support. Also, the prior art does not disclose the use of a lift device to assist in lifting and supporting the major components away from the base section to facilitate removal, cleaning and replacement of the dryer components.
SUMMARY OF THE INVENTION
The present invention is a centrifugal pellet dryer for removing surface moisture from resin pellets (approximately 0.015 to approximately 0.25 inches in diameter) and is specifically adapted for use in laboratory applications. The centrifugal pellet dryer of this invention distinguishes from currently available centrifugal pellet dryers which are not suitable for laboratory applications or other small operations. The instant pellet dryer is capable of operation at very low volume rates and is constructed with an overall size and characteristics for easy cleaning which make it desirable for laboratory applications.
The centrifugal pellet dryer of this invention includes a sectional housing having separable sections that are quickly and easily connected together and disconnected from each other. The separable sections are preferably cylindrical top and base sections connected by mating external peripheral flanges that are bolted together. The base section attaches to a top wall of a tank into which the water from the water and pellet slurry is drained, thereby eliminating the necessity of providing any piping system to remove the water from the dryer once separated from the pellets.
The centrifugal pellet dryer of this invention also includes a driven rotor that has a single supporting bearing at the upper end thereof with only an alignment bushing assembly at its lower end. A motor is preferably mounted atop a top plate to which the upper housing section is attached. The rotor supporting bearing is preferably mounted to the top plate and the alignment bushing assembly is preferably part of the lower or base housing section. This structure eliminates the necessity of providing a bottom bearing for the rotor and a sealing arrangement for the bottom bearing to preclude water from entering the bottom bearing thereby simplifying the structure. It also facilitates the easy separation and assembly of the top and base sections relative to each other.
Further, the centrifugal pellet dryer of this invention includes a lift device, preferably in the form of a gas spring lift and support device, to lift the motor, rotor, top plate and upper housing section upwardly away from the lower or base housing section which allows the lifted components to be swung about a vertical axis away from the base section. This lifting, supporting and swinging structure enables removal of the upper section of the housing and screen to facilitate cleaning of the exposed bladed rotor as it remains connected to its driving shaft.
The centrifugal pellet dryer of this invention also preferably includes a cylindrical one-piece screen which is telescopically engaged with recessed end edges on top and bottom support structures. The screen also includes support hooks engaging the top support structure to removably support the screen within the top and base sections of the housing to facilitate assembly and disassembly of the screen in the dryer. Additionally, the tank has a screen bottomed drawer receiving water from the base section of the dryer for removing any solid material or pellets which may be entrained in the water.
Accordingly, it is an object of the present invention to provide a centrifugal pellet dryer for removing surface moisture from pelletized product that is constructed uniquely for use in laboratory applications and other small operations. The pellet dryer of this invention includes a sectional housing in which multiple sections are connected by external flanges that are bolted together to enable quick and easy assembly and disassembly of the housing. The pellet dryer housing includes a base section constructed to communicate directly to a debris separating drawer on a top wall of a water drain tank thereby eliminating the necessity of providing a piping system to drain water from the dryer.
Another object of the present invention is to provide a pellet dryer in which the rotor is rigid with a shaft supported by a single upper bearing and having an alignment bushing assembly guiding rotation of the lower end of the rotor thereby eliminating the need for a sealing device or special waterproof design to protect a bottom bearing from water within the dryer.
A further object of this invention is to provide a centrifugal pellet dryer for laboratory applications as set forth in the preceding objects in which the dryer is capable of operation at very low volume rates and is constructed of a relatively overall small size and of separable and replaceable components rendering it easily cleanable, repairable and otherwise well suited for laboratory or small applications.
A still further object of the invention is to provide a gas lift for supporting and lifting the motor, the rotor and the upper housing section away from the base section when the dryer is being disassembled for repair and cleaning.
Still anoth
Bryan David E.
Dudding Carl M.
Bennett Henry
Gala Industries Inc.
Jacobson Price Holman & Stern PLLC
Wilson Pamela A.
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