Combustible fuel pellets formed from botanical material

• US 4,324,561 A
• Filed: 07/24/1980
• Issued: 04/13/1982
• Est. Priority Date: 06/26/1975
• Status: Expired due to Term

• Current Assignee: Nipac Limited
• Original Assignee: Nipac Limited
• Inventors: Dean, John J., Helzig, Lloyd M.
• Primary Examiner(s): Dees, Carl F.
• Application Number:
  US06/171,730
• Time in Patent Office: 628 Days
• Field of Search: 44/1 E, 44/10 A, 44/10 E, 44/10 B, 44/10 H
• US Class Current: 44/589
• CPC Class Codes: B30B 11/201 for extruding material
• CPC Class Codes: B30B 11/26 using press rams
• CPC Class Codes: B30B 11/28 using perforated rollers or discs
• CPC Class Codes: C10L 5/44 on vegetable substances
• CPC Class Codes: Y02E 50/10 Biofuels, e.g. bio-diesel
• CPC Class Codes: Y02E 50/30 Fuel from waste, e.g. synthetic alcohol or diesel

Abstract

A process and apparatus for pelletizing tree bark and other botanical material for use as an industrial fuel. A dryer burning fines from the final product is used to heat bark or other botanical material which is typically a waste product from lumbering or agricultural production. Once dried, the material is finely ground, preheated and forced through a pelletizing mill to create a pelletized product having a diameter of approximately 0.635 cm. The pellets are then cooled and leave the process. Several pelletizing mills are disclosed which are situated to trap the dried material against at least one die such that there will be a continuous, positive feed of material into the die. The resulting product may be substituted for coal as a heating source.

Claims

1. A combustible fuel pellet formed from botanical material including fiberized material, fines and bonding substances contained in the botanical materials, said pellet having a symmetrical configuration produced by passing the material under positive feed conditions through a constricted and elongated passage to heat and uniformly bond the fibers and bonding materials and densify the pellet, the cross-section dimension of formed pellet being not more than one-half inch, the density of the pellet being substantially uniform throughout the major portion thereof and in excess of 65 pounds per cubic foot, the surface of the pellet being smooth, and having a coating formed on the surface thereof from the natural bonding substances exuded from the botanical material, the produced pellet being relatively dry with an average moisture content of approximately 10% and the heat value of the pellet developing a BTU value approximating the bone dry BTU value of the material from which the pellet is formed.

2. A combustible fuel product as in claim 1 wherein the pellet is formed from tree bark.

3. A combustible fuel product as in claim 1 wherein the pellet is formed from wood fibers.

4. A combustible fuel pellet as in claim 1 wherein the pellet is formed from a composition of tree bark and wood fibers.

5. Combustible fuel pellets formed from botanical fuel material produced by reducing the moisture content of the material to an average of approximately 12 percent, grinding the dried material to a size sufficiently small to pass through a screen having openings no greater than 0.95 cm., heating the ground material to within an average range of 90°

C. to 121°

C., forcing the dried, ground and heated material under substantial pressure and friction through extrusion passages having a cross-section not exceeding approximately 0.635 cm. and while being forced through the passages compacting the material to substantially increase the density of the formed pellets and simultaneously reducing the moisture content to approximately 10 percent and increasing the temperature of the pellets thereby causing the natural bonding agents in the material to plasticize throughout substantially the length and diameter of the formed pellets so as to produce a bonded pellet product having a smooth and plasticized surface coating and the formed pellets having the required properties and characteristics to provide an extended storage and shipping life in an atmospheric environment.