Post torrefaction biomass pelletization

• US 9,057,037 B2
• Filed: 10/31/2012
• Issued: 06/16/2015
• Est. Priority Date: 04/20/2010
• Status: Active Grant

• Current Assignee: Biomass Secure Power Inc.
• Original Assignee: River Basin Energy, Inc. (Biomass Secure Power Inc.)
• Inventors: Camper, Clinton B., Sethi, Vijay, Isaak, Jerrod D.
• Primary Examiner(s): Toomer, Cephia D
• Application Number:
  US13/665,886
• Publication Number:
  US 20130055631A1
• Time in Patent Office: 958 Days
• Field of Search: 445/89
• US Class Current: 1/1
• CPC Class Codes: C10B 49/10 according to the "fluidised bed" technique
• CPC Class Codes: C10B 53/02 of cellulose-containing material production of pyroligneous acid C10C5/00
• CPC Class Codes: C10L 2290/02 Combustion or pyrolysis
• CPC Class Codes: C10L 2290/06 Heat exchange, direct or indirect
• CPC Class Codes: C10L 2290/08 Drying or removing water
• CPC Class Codes: C10L 2290/20 Coating of a fuel as a whole or of a fuel component
• CPC Class Codes: C10L 2290/28 Cutting, disintegrating, shredding or grinding
• CPC Class Codes: C10L 2290/30 Pressing, compressing or compacting
• CPC Class Codes: C10L 2290/50 Screws or pistons for moving along solids
• CPC Class Codes: C10L 2290/58 Control or regulation of the fuel preparation of upgrading process
• CPC Class Codes: C10L 5/08 without the aid of extraneous binders briquetting peat C10F
• CPC Class Codes: C10L 5/32 Coating
• CPC Class Codes: C10L 5/361 Briquettes
• CPC Class Codes: C10L 5/363 Pellets or granulates
• CPC Class Codes: C10L 5/447 Carbonized vegetable substances, e.g. charcoal, or produced by hydrothermal carbonization of biomass
• CPC Class Codes: C10L 9/083 Torrefaction
• 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
• CPC Class Codes: Y02P 20/145 the feedstock being materials of biological origin

Abstract

A process for torrefaction of biomass is provided in which biomass are passed into a fluidized bed or a non-fluidized bed reactor and heated to a predetermined temperature in an oxidizing environment. The dried biomass is then fed to a cooler where the temperature of the product is reduced to approximately 100 degrees Fahrenheit.

Claims

1. A process for biomass torrefaction, comprising:

adding biomass to a reactor;

adding a gas to the reactor;

controlling an oxygen content of the gas;

initiating heating of the biomass by increasing a temperature of the reactor;

heating the biomass;

maintaining the biomass within the reactor for a predetermined time;

removing water from the biomass;

vaporizing volatile organic compounds associated with the biomass;

torrefying the biomass;

combusting the volatile organic compounds to help maintain the temperature of the reactor; and

forming the torrefied biomass into pellets at a temperature of about 90°

C. to 200°

C.

2. The process of claim 1, wherein the heating is achieved by the combustion of the volatile organic compounds.

3. The process of claim 1, wherein the biomass is not primarily heated by external sources after the initiating.

4. The process of claim 1, wherein the biomass has an average moisture content of from about 10 to about 50 percent and the reactor is not fluidized.

5. The process of claim 1, wherein a pressure within the reactor is near ambient.

6. The process of claim 1, wherein the temperature of the reactor is held from about 230 to about 350 degrees Centigrade for the predetermined period of time.

7. The process of claim 1, further comprising grinding the biomass to a maximum size of about 1.5 in.×

1.5 in.×

0.4 in.

8. The process of claim 1, further comprising pelletizing the torrefied biomass to a diameter of about 0.25 inch.

9. The process of claim 1, wherein the initiating entails raising the temperature of the reactor by a startup procedure comprising:

providing a starting heater;

slowly increasing heat within the reactor with the starting heater;

feeding the biomass to the reactor when the temperature of the reactor is between about 275 to 315 degrees C.;

releasing heat from the biomass by combustion thereof; and

adding small amounts of the biomass to the reactor to maintain a steady rise in temperature.

10. The process of claim 1, further comprising:

feeding the torrefied biomass into a cooler where it is cooled to a temperature near 100 degrees Centigrade by adding no more than 3% moisture to the torrefied biomass.

11. The process of claim 1, further comprising:

feeding the torrefied biomass to a holding vessel before forming into pellets.

12. The process of claim 1, further comprising:

feeding heated torrefied biomass directly to a pelletizing device.

13. The process of claim 1, wherein the heat used to form the torrefied biomass into pellets is obtained from the reactor.

14. The process of claim 1, wherein the reactor is a fluidized bed reactor.

15. The process of claim 1, wherein the gas comprises recycled off-gas.

16. The process of claim 1, wherein the gas comprises air and recycled off-gas.

17. The process of claim 16, wherein an aspect ratio of the fluidized bed reactor between about ⅓

and about 2.

18. The process of claim 1, wherein a gas velocity of the gas is between about 4 feet per second and about 8 feet per second.

19. The process of claim 1, wherein the predetermined time is between about 5 minutes and about 30 minutes.

20. The process of claim 1, wherein a temperature of the reactor is between about 270°

C. to about 300°

C.