Method for Making Biomass Pellets

• US 20110041390A1
• Filed: 09/21/2009
• Published: 02/24/2011
• Est. Priority Date: 08/20/2009
• Status: Active Grant

• Current Assignee: Brdc, LLC
• Original Assignee: Show Me Energy
• Inventors: Dowell, J.D., Flick, Steve A., Herman, Kurt
• Granted Patent: US 9,453,176 B2
• Time in Patent Office: Days
• US Class Current: 44/589
• CPC Class Codes: C10L 2200/0469 Renewables or materials of biological origin
• CPC Class Codes: C10L 2290/30 Pressing, compressing or compacting
• CPC Class Codes: C10L 5/363 Pellets or granulates
• CPC Class Codes: C10L 5/44 on vegetable substances
• CPC Class Codes: C10L 5/445 Agricultural waste, e.g. corn crops, grass clippings, nut shells or oil pressing residues
• 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

The present invention is directed to a process for forming biomass pellets using biomass feedstock having predetermined characteristics to form biomass pellets having desired characteristics. The process can utilize feedstock derived from a variety of biomass feedstock sources, including wood, agricultural crops, energy crops and weeds, alone or in combination.

Claims

1. A method for making biomass pellets, comprising the steps of:

selecting biomass feedstock from at least one feedstock fraction having a known moisture composition and net energy value in an amount to produce pellets having a predetermined net energy value and moisture content; and

forming said feedstock into pellets.

2. The method of claim 1, wherein said one feedstock fraction comprises feedstock derived from the group comprising Switchgrass, INDIANGRASS, BIG BLUESTEM, Broadleaf weeds, grass straws, CORNSTALKS, dedicated energy crops, and seed residue.

3. The method of claim 1, wherein said one feedstock fraction comprises feedstock derived from a dedicated energy crop.

4. The pellets formed by the method of claim 1.

5. A method for making biomass pellets, comprising the steps of:

selecting biomass feedstock from at least two feedstock fractions, each having a known moisture composition and net energy value, in relative amounts to produce pellets having a predetermined net energy value and moisture content; and

forming said feedstock into pellets.

6. The method of claim 5, wherein at least one of said feedstock fractions comprises feedstock derived from the group comprising Switchgrass, INDIANGRASS, BIG BLUESTEM, Broadleaf weeds, grass straws, CORNSTALKS, dedicated energy crops, and seed residue.

7. The method of claim 5, wherein at least one of said feedstock fractions comprises feedstock derived from dedicated energy crop.

8. The method of claim 7, wherein at least one of said feedstock fractions comprises feedstock derived from the group comprising wood and agricultural crops.

9. The pellet formed by the method of claim 5.

10. A method for forming a biomass pellet comprising the steps of:

selecting biomass feedstock from at least one feedstock fraction having a known moisture composition and net energy value in an amount to produce pellets having a predetermined net energy value and moisture content;

grinding said feedstock in a hammer mill;

removing SiO₂ and other impurities from said feedstock using exchange plates; and

forming said feedstock into pellets.

11. The method of claim 10, wherein said grinding step utilizes hammer mill blade speeds between 1750 and 2100 RPM.

12. The method of claim 11, wherein said grinding step heats said feedstock to a temperature of at least 190 degrees F.

13. The method of claim 10, further comprising, prior to said forming step, the step of conditioning said feedstock by heating said feedstock without the addition of moisture or conditioning agents.

14. The method of claim 13, wherein said conditioning step comprises heating said feedstock to a temperature above 210 degrees F.

15. The method of claim 10, wherein at least one of said feedstock fractions comprises feedstock derived from the group comprising Switchgrass, INDIANGRASS, BIG BLUESTEM, Broadleaf weeds, grass straws, CORNSTALKS, dedicated energy crops, and seed residue.

16. The method of claim 10, wherein at least one of said feedstock fractions comprises feedstock derived from a dedicated energy crop.

17. The method of claim 10, further comprising, prior to said selecting step, the step of determining the net energy value and moisture content of said feedstock fractions, and wherein said determining and selecting steps are performed by an automated process.

18. The method of claim 10, further comprising prior to said selecting step, the step of processing biomass feedstock bales by rotating said bales clockwise and counterclockwise into a hammer mill grinder apparatus to form at least one of said feedstock fractions.

19. The method of claim 10, wherein said forming step comprises extruding said feedstock through an extruder pellet die operating at 150-175 degrees F. with a die size of I.D. 34 13/16″

, O.D. 42 13/16″

, 13″

overall die tract, 120 mm die, with a thickness of 4 inches.

20. The pellet formed by the process of claim 10.

21. A method for forming a biomass pellet comprising the steps of:

selecting biomass feedstock from at least one feedstock fraction having a known moisture composition and net energy value in an amount to produce pellets having a predetermined net energy value and moisture content;

grinding said feedstock in a hammer mill;

transferring said feedstock to a holding bin using a moving air stream, wherein SiO₂ and other impurities are removed from the airstream using exchange plates;

conditioning said feedstock in said holding bin using dry radiant heat; and

forming said conditioned feedstock into pellets.