Agricultural fibre fuel pellets

• US 20080172933A1
• Filed: 11/15/2007
• Published: 07/24/2008
• Est. Priority Date: 05/16/2005
• Status: Active Grant

• Current Assignee: Evergreen Biofuels, Inc.
• Original Assignee: Evergreen Biofuels, Inc.
• Inventors: Lapointe, Claude, Drisdelle, Mark
• Granted Patent: US 7,785,379 B2
• Time in Patent Office: Days
• US Class Current: 44/535
• CPC Class Codes: C10L 1/1233 oxygen containing compounds, e.g. oxides, hydroxides, acids and salts thereof
• CPC Class Codes: C10L 1/1266 nitrogen containing compounds, (e.g. NH3)
• CPC Class Codes: C10L 1/1291 Silicon and boron containing compounds
• CPC Class Codes: C10L 5/363 Pellets or granulates
• CPC Class Codes: C10L 5/44 on vegetable substances
• CPC Class Codes: C10L 9/08 by heat treatments, e.g. calcining
• CPC Class Codes: C10L 9/10 by using additives
• 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 method of preparing fuel pellets includes the steps of providing a feedstock in the form of agricultural hull fibres having a moisture content of about 10 to about 16%; and compressing and extruding the agricultural fibre feedstock through a die to obtain fuel pellets in the form of small cylinders having a diameter of about ⅜ inch to ¾ inch or more, said pellets having an ash content of about 1.1% to about 20% by weight and a calorific value of about 7,000 BTUs per pound of fuel on a dry basis. The agricultural hull fibres may be derived from all whole grains and seeds. For example, are comprised of at least one of corn bran fibre, rye bran fibre; oat bran fibre, rice bran fibre, soy bran fibre, canola bran fibre and wheat bran fibre. The method may include the step of pre-treating the agricultural whole grain and seed hull fibre feedstock with high temperature steam before being formed into pellets at a sufficient temperature and sufficient time to activate hemicellulose within the fibre as a binding agent. The method may include the step of mixing the agricultural whole grain and seed hull fibre feedstock with a sequestering agent before being formed into pellets for sequestering alkali metal vapors and raising the fusion point of the inorganic elements during combustion of the pellets. The sequestering agent may be calcium carbonate added in amounts up to about 0.5% by weight. The pellets contain additives comprised of ammonium nitrate, calcium, manganese, magnesium, aluminum, barium, iron, potassium and amorphous silicate, which sequester potassium and chlorides and alter the fusion point of the inorganic elements present in the fuel.

Claims

1. A method of preparing fuel pellets comprising the steps of:

providing a feedstock in the form of agricultural hull fibres having a moisture content of about 10 to about 16%; and

compressing and extruding the agricultural fibre feedstock through a die to obtain fuel pellets in the form of small cylinders having a diameter of about ⅜

inch to ¾

inch or more, said pellets having an ash content of about 1.1% to about 20% by weight and a calorific value of about 7,000 BTUs per pound of fuel on a dry basis

2. A method according to claim 1 wherein the agricultural hull fibres derived from all whole grains and seeds are comprised of at least one of corn bran fibre, rye bran fibre;

oat bran fibre, rice bran fibre, soy bran fibre, canola bran fibre (rape seed) and wheat bran fibre

3. A method according to claim 1 including the step of pre-treating the agricultural whole grain and seed hull fibre feedstock with high temperature steam before being formed into pellets.

4. A method according to claim 3 wherein the pre-treating step is at a sufficient temperature and sufficient time to activate hemicellulose within the fibre as a binding agent.

5. A method according to claim 1 including the step of mixing the agricultural whole grain and seed hull fibre feedstock with a sequestering agent before being formed into pellets for sequestering alkali metal vapors and raising the fusion point of the inorganic elements during combustion of the pellets.

6. A method according to claim 5 wherein the sequestering agent is calcium carbonate.

7. A method according to claim 6 wherein the calcium carbonate is added in amounts up to about 0.5% by weight.

8. A method according to claim 1 wherein the temperature is raised to at least about 130°

C. or more during extrusion of the agricultural whole grain and seed hull fibre feedstock through the die.

9. A method according to claim 1 wherein the agricultural whole grain and seed hull fibres have a length of less than about ^3/ inch.

10. A method according to claim 1 wherein the pellets have a length of less than about 2 inches.

11. A method according to claim 1 wherein the pellets have a moisture content in the range of about 3 to about 10%

12. A method according to claim 1 wherein the agricultural hull fibre feedstock has a bulk density of about 11 to about 16 pounds per cubic foot.

13. A method according to claim 1 wherein the pellets obtained have a bulk density of about 40 to 70 pounds per cubic foot.

14. A method according to claim 1 wherein pellets are obtained contain less about 300 ppm of water soluble chlorides and are sequestered during combustion of the fuel pellets.

15. A method according to claim 1 wherein the agricultural hull fibre pellets are formed at a throughput of feedstock of at least 100 pounds per hour per horsepower of extrusion energy consumed.

16. A method according to claim 5 wherein the pellets contain additives comprised of ammonium nitrate, calcium, manganese, magnesium, aluminum, barium, iron, potassium and amorphous silicate, which sequester potassium and chlorides and alter the fusion point of the inorganic elements present in the fuel.

17. A fuel pellet derived from the fibres of whole grains and seeds comprising:

agricultural hull fibres;

a binding agent including steam activated hemicellulose a sequestering agent to control alkali metal vapours additives to alter the fusion point of the inorganic elements

18. A fuel pellet according to claim 17 wherein the sequestering agent is calcium carbonate

19. A fuel pellet according to claim 18 wherein the calcium carbonate is added in amounts up to about 0.5% by weight.

20. A fuel pellet according to claim 17 wherein the agriculture fuel pellets from hull fibres have a length of about ^3/ inch.

21. A fuel pellet according to claim 17 wherein the pellets have a length of less than about 2 inches.

22. A fuel pellet according to claim 17 wherein the pellets have a moisture content in the range of about 3 to 12%.

23. A fuel pellet according to claim 17 wherein the pellets obtained have a bulk density of about 40 to 70 pounds per cubic foot.

24. A fuel pellet according to claim 17 wherein pellets are obtained containing less than 300 ppm of water soluble chlorides.

25. A fuel pellet according to claim 17 wherein the pellets contain additives comprised of ammonium nitrate, calcium, manganese, magnesium, aluminum, barium, iron, potassium and amorphous silicate, which sequester potassium and chlorides and alter the fusion point of the inorganic elements present in the fuel.