METHOD AND SYSTEM FOR THE TORREFACTION OF LIGNOCELLULOSIC MATERIAL

• US 20110041392A1
• Filed: 07/08/2010
• Published: 02/24/2011
• Est. Priority Date: 08/19/2009
• Status: Active Grant

• Current Assignee: Andritz Technology and Asset Management GmbH
• Original Assignee: Andritz Technology and Asset Management GmbH
• Inventors: STROMBERG, Bertil, RAWLS, Joseph Monroe
• Granted Patent: US 8,449,724 B2
• Time in Patent Office: Days
• US Class Current: 44/607
• CPC Class Codes: C10L 5/363 Pellets or granulates
• CPC Class Codes: C10L 5/44 on vegetable substances
• 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

Abstract

Systems and methods for producing torrefied lignocellulosic material in a commercially suitable process.

Claims

1. A system for the torrefaction of lignocellulosic material comprising:

a dryer for drying lignocellulosic material adapted to remove at least of a portion of moisture contained within the lignocellulosic material;

a torrefaction reactor adapted to operate at a pressure between 1 and 50 bar and at a temperature between 100 and 1000°

C., wherein the torrefaction reactor generates torrefied biomass from the lignocellulosic material and generates torrefaction gas;

a first recycle loop adapted to recycle torrefaction gas back to the torrefaction reactor;

a cooler adapted to cool torrefied biomass, wherein the cooler is adapted to operate in a substantially oxygen-free environment;

a second recycle loop adapted to recycle inert gas to the cooler and to provide inert gas to the torrefaction reactor; and

a supply line adapted to supply inert gas for addition to the cooler;

wherein the system is adapted to use the inert gas as at least a partial medium for transferring heat among the torrefaction reactor and the cooler.

2. The system of claim 1, wherein the cooler is a fluidbed cooler, and wherein the system further comprises a cyclone adapted to separate the cooled torrefied biomass from an inert gas.

3. The system of claim 1, wherein the inert gas comprises nitrogen.

4. The system of claim 1, wherein the dryer is adapted to remove moisture present in the lignocellulosic material such that an absolute moisture content of the lignocellulosic material is less than 15% of the total weight of the lignocellulosic material.

5. The system of claim 1, wherein the dryer employs energy received from a hot gas at a temperature of up to 1,000°

C.

6. The system of claim 1, wherein the torrefaction reactor operates at between 5 and 20 bar.

7. The system of claim 1, wherein the torrefaction reactor operates at a temperature of about 220-300°

C.

8. The system of claim 1 further comprising a pelletizer for compacting torriefied biomass solids obtained from the cooler.

9. The system of claim 1 further comprising an air separator for separating air into at least a first stream comprising oxygen and a second stream comprising nitrogen, wherein the nitrogen is used as the inert gas.

10. The system of claim 1 further comprising a combustion unit for combusting at least oxygen and a portion of the torrefaction gas produced in the torrefaction reactor.

11. The system of claim 10, wherein the combustion unit produces a flue gas supplied to the dryer for drying lignocellulosic material.

12. A method for the torrefaction of lignocellulosic material comprising the steps of:

drying lignocellulosic material to remove at least a portion of moisture contained within the lignocellulosic material;

reacting the dried lignocellulosic material at a pressure between 1 and 50 bar and at a temperature between 100 and 1000°

C. in a torrefaction reactor to generate torrefied biomass and torrefaction gas;

recycling at least a portion of the torrefaction gas back to the torrefaction reactor;

cooling the torrefied biomass in a cooler operating in a substantially oxygen-free environment;

recycling inert gas to the cooler and recycling inert gas to the torrefaction reactor;

supplying make-up inert gas to the cooler;

wherein the method uses the inert gas as at least a partial medium for transferring heat among the torrefaction reactor and the cooler.

13. The method of claim 12, wherein the cooler is a fluidbed cooler, and wherein the method further comprises a step of separating the torriefied biomass and inert gas in a cyclone.

14. The method of claim 12, wherein the inert gas comprises nitrogen.

15. The method of claim 12, wherein the step of drying removes moisture present in the lignocellulosic material such that an absolute moisture content of the lignocellulosic material is less than 15% of the total weight of the lignocellulosic material.

16. The method of claim 12 further comprising the step of combusting at least oxygen and a portion of the torrefaction gas produced in the torrefaction reactor to produce a hot flue gas.

17. The method of claim 16 further comprising the step of providing the hot flue gas to the dryer at a temperature of up to 1,000°

C.

18. The method of claim 12 further comprising the step of compacting in a pelletizer the torriefied biomass solids obtained from the cooler.

19. The method of claim 12 further comprising the steps of separating air into at least a first stream comprising oxygen and a second stream comprising nitrogen and using the nitrogen as the inert gas.

20. The method of claim 12, wherein reacting the dried lignocellulosic material occurs at a pressure between 5 and 20 bar.