METHOD AND SYSTEM FOR THE TORREFACTION OF LIGNOCELLULOSIC MATERIAL

• US 20120042567A1
• Filed: 08/16/2011
• Published: 02/23/2012
• Est. Priority Date: 08/17/2010
• Status: Abandoned Application

• Current Assignee: Andritz Technology and Asset Management GmbH
• Original Assignee: Andritz Technology and Asset Management GmbH
• Inventors: Stromberg, Bertil, Weston, John, RAWLS, Joseph, Jiang, Xiaoping, Hunt, Tyson
• Application Number:
  US13/210,980
• Publication Number:
  US 20120042567A1
• Time in Patent Office: Days
• US Class Current: 44/606
• CPC Class Codes: C10L 5/44 on vegetable substances
• 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

A method for torrefaction of lignocellulosic biomass using a torrefaction reactor vessel having stacked trays, the method including: continuously feeding the biomass to an upper inlet of the torrefaction reactor vessel such that the biomass material is deposited on an upper tray of a plurality of trays stacked vertically within the reactor; as the biomass moves across an upper surface of each of the trays, heating and drying the biomass material with a gas injected into the vessel, wherein the gas is substantially non-oxidizing of the biomass, is under a pressure of at least 20 bar gauge and at a temperature of at least 200° C.; cascading the biomass down through the trays by passing the biomass through an opening in each of the trays to deposit the biomass on a lower tray; discharging torrefied biomass from a lower outlet of the torrefaction reactor vessel, and circulating gas extracted from a lower elevation of the reactor vessel to an upper region of the reactor vessel.

Claims

1. A method for torrefaction of lignocellulosic biomass using a torrefaction reactor vessel having stacked trays, the method comprising:

continuously feeding the biomass to an upper inlet of the torrefaction reactor vessel such that the biomass material is deposited on an upper tray of a plurality of trays stacked vertically within the reactor;

as the biomass moves across an upper surface of each of the trays, heating and drying the biomass material with a gas injected into the vessel, wherein the gas is substantially non-oxidizing of the biomass, is under a pressure of at least 20 bar gauge and at a temperature of at least 200°

C., and

cascading the biomass down through the trays by passing the biomass through an opening in each of the trays to deposit the biomass on a lower tray;

discharging torrefied biomass from a lower outlet of the torrefaction reactor vessel, and

circulating gas extracted from a lower elevation of the reactor vessel to an upper region of the reactor vessel.

2. The method of claim 1 wherein the gas is at least one of superheated steam, carbon dioxide and nitrogen.

3. The method of claim 1 further comprising a pressurizing the biomass before the feeding of the biomass into the vessel with a pressure transfer device.

4. The method of claim 1 wherein at least the upper trays are a mesh, screen or have perforations and the heating and drying of the biomass includes passing the gas through the biomass and the trays.

5. The method of claim 4 wherein the trays below the upper trays are solid such that the gas does not pass through the tray.

6. The method of claim 1 wherein the lower elevation of the vessel where the gas is extracted is adjacent a lower tray of the trays.

7. The method of claim 1 wherein gas is injected into the vessel at two elevations wherein the gas is hotter when injected at a lower elevation of the two elevations than the gas injected at an upper elevation of the two elevations.

8. The method of claim 1 wherein below an elevation of the vessel from which the gas is extracted, the biomass continues to cascade down through at least one of the trays.

9. The method of claim 1 further comprising injecting the gas in the biomass to purge oxygen from the biomass.

10. The method of claim 9 wherein the injection occurs before the biomass enters the vessel or as the biomass enters the vessel.

11. A torrefaction pressurized reactor vessel assembly comprising:

a stack of trays housed within the vessel;

a source of a pressurized, reduced oxygen gas coupled to the vessel to allow the gas to flow into at least an upper region of the vessel, wherein the gas is at a pressure of at least 20 bar gauge and at a temperature of at least 200°

C.;

an upper inlet to the vessel through which biomass enters the pressurized reactor vessel, wherein a chute aligned with the upper inlet directs the biomass from the inlet to an upper tray of the stack of trays;

a scraper device associated with an upper surface on each of the trays, wherein at least one of the scraper device and tray rotates within the vessel;

a lower outlet in the vessel through which torrefied biomass is discharged from the torrefaction reactor vessel, and

a gas circulation system through which gas extracted from a lower elevation in the vessel flow to an upper elevation of the reactor vessel.

12. The torrefaction pressurized reactor vessel assembly of claim 11 wherein the wherein the source of a pressurized, reduced oxygen gas is a source of at least one of superheated steam, carbon dioxide and nitrogen.

13. The torrefaction pressurized reactor vessel assembly of claim 11 further a pressure transfer device which pressurizes and feeds the biomass to the reactor vessel.

14. The torrefaction pressurized reactor vessel assembly of claim 11 wherein at least one of the upper trays of the stack of trays is a mesh, screen or has perforations.

15. The torrefaction pressurized reactor vessel assembly of claim 14 wherein trays below the upper trays are solid such that the gas does not pass through the tray.

16. The torrefaction pressurized reactor vessel assembly of claim 11 wherein a lower elevation of the vessel at where the gas is extracted for circulation is adjacent a lower tray.

17. The torrefaction pressurized reactor vessel assembly of claim 11 wherein the gas circulation system further comprises a heat exchanger.

18. The torrefaction pressurized reactor vessel assembly of claim 11 further comprising a vertical rotating shaft extending through a center axis of the reactor vessel and at least one of the scraper device and trays are fixed to the shaft.

19. The torrefaction pressurized reactor vessel assembly of claim 11 wherein the reactor vessel includes a lower region devoid of trays and receiving the biomass material.

20. The torrefaction pressurized reactor vessel assembly of claim 11 further comprising biomass supply bin a conduit conveying the pressurized, reduced oxygen gas to the biomass supply bin.