Method and system for processing lignocellulose material

Patent metadata

Field	Value
Publication number	US-11319603-B2
Application number	US-201816762570-A
Country	US
Kind code	B2
Filing date	Sep 21, 2018
Priority date	Nov 9, 2017
Publication date	May 3, 2022
Grant date	May 3, 2022

Abstract

A method for processing lignocellulose materials comprising the steps of hydrothermal treatment of the material with saturated or superheated steam in a hydrothermal pressure vessel, wherein the steam is provided by means of a steam boiler. The treatment is performed at a pressure of 5-30 bars, and at a temperature of 160-240° C. for a duration of 1-20 minutes. The method further comprises discharging hydrothermally treated lignocellulose material and steam from the pressure vessel by means of rapid pressure reduction, separating the steam and vapours released from the lignocellulose material, and burning the vapours together with additional fuel and combustion air in the furnace of said steam boiler. Furthermore, a corresponding system is provided.

First claim

The invention claimed is:

1. A method for processing lignocellulose material, comprising hydrothermal treatment of said material with saturated or superheated steam in a hydrothermal pressure vessel, wherein said treatment is performed continuously at a pressure of 5-30 bars, and at a temperature of 160-240° C. for a duration of 1-20 minutes, wherein said saturated or superheated steam is provided from a steam supplier comprising a steam boiler, said method further comprising:
discharging hydrothermally treated lignocellulose material and steam from the hydrothermal pressure vessel by pressure reduction;
separating steam and vapours released from said lignocellulose material;
burning said vapours together with additional fuel and combustion air in a furnace of said steam boiler;
recovering latent heat of condensation from flue gas from said steam boiler with a condensing flue gas cooler; and
using the recovered heat from the flue gas cooler for drying of the lignocellulose material prior to being supplied to said hydrothermal pressure vessel,
wherein the method is performed continuously in the hydrothermal pressure vessel,
wherein the method is performed without a condenser arranged between the hydrothermal pressure vessel and the furnace of said steam boiler.

2. The method according to claim 1 , further comprising providing said saturated or superheated steam directly from said steam boiler, and using the condensate formed during cooling of the flue gas as make-up water in the steam cycle.

3. The method according to claim 1 , wherein said steam supplier further comprises a steam reboiler, and wherein said method further comprises using the condensate formed during cooling of the flue gas as make-up water to said steam reboiler for production of steam to the hydrothermal pressure vessel using condensing fresh steam from the steam boiler as heating media.

4. The method according to claim 2 , wherein said condensate is cleaned prior to use as make-up water.

5. The method according to claim 1 , wherein the dryness of the lignocellulose material fed to the hydrothermal pressure vessel is 0-30% on wet weight basis.

6. The method according to claim 1 , wherein said separating is performed using at least one cyclone.

7. The method according to claim 1 , further comprising the step of densifying of the hydrothermally treated lignocellulose material to form fuel pellets or briquettes.

8. The method according to claim 1 , further comprising using the recovered heat from the flue gas cooler for drying of the lignocellulose material discharged from said hydrothermal pressure vessel.

9. A system for processing lignocellulose material, comprising
at least one hydrothermal pressure vessel adapted for continuous hydrothermal treatment of said lignocellulose material;
a steam supplier connected to at least one of said at least one hydrothermal pressure vessel to supply steam thereto, said steam supplier comprising at least one steam boiler;
a discharge orifice or blow valve arranged at an outlet of each hydrothermal pressure vessel, said orifice or blow valve being adapted for pressure reduction to atmospheric pressure;
a separator connected to the discharge orifice or blow valve adapted for separating steam and vapours from said lignocellulose material, said separator further being connected to a furnace of said steam boiler to allow combustion of said vapours together with additional fuel and combustion air therein;
at least one flue gas cooler connected to the steam boiler to recover latent heat of condensation from flue gas from said steam boiler; and
at least one pre-dryer connected to the at least one hydrothermal pressure vessel to dry the lignocellulose material prior to being supplied to said hydrothermal pressure vessel, wherein said at least one flue gas cooler is connected to said at least one pre-dryer to provide recovered heat thereto,
wherein the system is configured to perform the processing continuously in the at least one hydrothermal pressure vessel,
wherein the system is arranged without a condenser arranged between the at least one hydrothermal pressure vessel and the furnace of said steam boiler.

10. The method according to claim 3 , wherein said condensate is cleaned prior to use as make-up water.

Assignees

• Valmet Oy

Inventors

• Björklund Peter
• Erixon Mattias
• Lambert Francois
• Averheim Andreas

Classifications

• Y02E50/10

  Biofuels, e.g. bio-diesel · CPC title

• C13K13/00 Primary

  Sugars not otherwise provided for in this class · CPC title

• C10L2200/0469

  Renewables or materials of biological origin · CPC title

• D21B1/021

  by chemical means · CPC title

• C10L2290/06

  Heat exchange, direct or indirect · CPC title