Method for treating lignocellulosic biomass by impregnation and steam explosion

Patent metadata

Field	Value
Publication number	US-11236403-B2
Application number	US-201716318581-A
Country	US
Kind code	B2
Filing date	Jul 11, 2017
Priority date	Jul 18, 2016
Publication date	Feb 1, 2022
Grant date	Feb 1, 2022

Abstract

The invention concerns a continuous method for treating a lignocellulosic biomass before enzymatic hydrolysis, said method comprising a transfer of crushed then pressed biomass to a step of impregnation by an acid liquor, the impregnated biomass dripping over the area containing the impregnation liquor, then the resulting wet biomass is pressed and sent to a steam explosion step. The impregnation liquor is prepared in a dedicated area from the used liquor from the dripping operation and/or that from the pressing operation, prior to the explosion step. The invention also concerns the facility for implementing the method.

First claim

The invention claimed is:

1. A continuous process for treating a lignocellulosic biomass for the production of sugary juices, carried out before an enzymatic hydrolysis, the process comprising:
1) in a first transfer zone, transferring a milled biomass to a first impregnation zone of an impregnation step, said first transfer zone and first impregnation zone being separated by a plug of biomass preventing liquid upflow from said first impregnation zone to the first transfer zone,
2) carrying out the impregnation step under atmospheric pressure in 2 superposed impregnation zones operating at a temperature of 10-95° C., the residence time of the biomass in said step being 1 min-60 min, and
said first impregnation zone receives the pressed biomass resulting from the first transfer zone and it contains an impregnation liquor having a pH of between 0.1 and 7,

and
transferring said biomass to a second impregnation zone, located above said first impregnation zone, in which the impregnated biomass is drained, so as to produce a resulting wet biomass having a total solids content of between 15 wt % and 40 wt %, and a separate liquor,

3) in a second transfer zone, transferring the wet biomass to a steam explosion step, the steam explosion step having each of a cooking zone which comprises a reactor, an expansion zone and a separating zone,
said second transfer zone being positioned in a chamber separated, on the one hand, from the impregnation zones of said impregnation step and, on the other hand, from the zones of the steam explosion step,
the second impregnation zone and the reactor of the steam explosion step being separated in a leaktight manner by a plug of biomass, and
in said second transfer zone, pressing the wet biomass so as to increase the total solids content of the biomass to 40% by weight or more, and produce a resulting liquor,

4) a steam explosion step comprising
cooking the biomass in the cooking zone for 1-30 min by injection of steam with a specific steam consumption of between 0.05 and 10 tonnes/tonne of biomass total solids entering said zone, said cooking zone being at a temperature of 150-250° C. and a pressure of 0.5-4 MPa,
then, in the expansion zone, expanding the biomass resulting from the cooking zone,
then, in the separation zone, separating the steam from the biomass,

5) a step of producing an acid liquor using a preparation device suitable for,
receiving the resulting liquor from the second transfer zone and/or from the first impregnation zone, and
receiving inputs of acid and/or water that are determined so as to maintain the pH at the inlet of the first impregnation zone at a value between 0.1 and 7,

and introducing said acid liquor into the first impregnation zone.

2. The process as claimed in claim 1 , wherein said impregnation step is carried out in a single step.

3. The process as claimed in claim 1 , wherein:
the impregnation step is carried out in 2 impregnation zones positioned vertically one above the other and along the same axis, separated so as to allow the liquor from the second zone to pass to the first impregnation zone and so as to retain the biomass in the second impregnation zone, the level of the liquid of the first impregnation zone ensuring the separation between said 2 zones, and
said biomass is transferred by means of a screw from said first impregnation zone into said second impregnation zone.

4. The process as claimed in claim 1 , wherein the liquor level is kept constant by input of acid liquor.

5. The process as claimed in claim 1 , wherein the acid liquor is only a solution of sulfuric acid.

6. The process as claimed in claim 1 , wherein the acid liquor has a pH of between 0.1 and 2.

7. The process as claimed in claim 1 , wherein said step of preparing the acid liquor receives liquor extracted from the second transfer zone and optionally liquor from the first impregnation zone.

8. The process as claimed in claim 1 , wherein said step of preparing the acid liquor receives liquor from the first impregnation zone and optionally liquor extracted from the second transfer zone.

9. The process as claimed in claim 1 , wherein, in said second transfer zone for transferring the wet biomass, the total solids content of the biomass after pressing is between 40% and 70% by weight.

10. The process as claimed in claim 1 , wherein the cooking zone is a horizontal tubular reactor, and is provided with one or more screws that transport the biomass from the second transfer zone upstream to the expansion zone downstream.

11. The process as claimed in claim 1 , wherein the milled biomass has a size of at most 300 mm.

12. The process as claimed in claim 1 , wherein at least one portion of the biomass resulting from the steam explosion step is subjected to an enzymatic hydrolysis and sugary juices are obtained.

13. The process as claimed in claim 12 , in which at least one portion of the sugary juices is subjected to an alcoholic fermentation.

14. The process as claimed in claim 1 , wherein, in said second transfer zone for transferring the wet biomass, the total solids content of the biomass after pressing is greater than 40%.

15. A unit for the continuous treatment of a lignocellulosic biomass before enzymatic hydrolysis, comprising:
1) a first transfer zone for transferring a milled biomass, with pressing, to a first impregnation zone of an impregnation reactor, said first transfer and first impregnation zones being separated by a plug of biomass preventing liquid upflow from said first impregnation zone to the first transfer zone,
2) an impregnation reactor comprising 2 superposed impregnation zones, the second impregnation zone being located above the first impregnation zone
said first impregnation zone containing an acid liquor and being provided with an inlet opening for the pressed biomass resulting from the first transfer zone,
the impregnation reactor being provided with a screw that transfers said biomass from said inlet opening in the first impregnation zone to an outlet opening of the second impregnation zone,
the second impregnation zone located above the liquor of the first impregnation zone and being provided with screen(s) that allow the liquid to flow from the second impregnation zone into the first impregnation zone and that retain a wet biomass wetted by the liquor in the second zone,

3) a second transfer zone for transferring the wet biomass, with pressing, to a steam explosion zone,
said second transfer zone being positioned in a chamber separated, on the one hand, from the impregnation zones and, on the other hand, from the steam explosion zone,
the second impregnation zone and the steam explosion zone being separated by a plug of pressed biomass so as to increase the total solids content of the biomass to 40% by weight or more, said plug preventing liquid upflow from said first zone to the second transfer zone, and
said second transfer zone being provided with a line for drawing off the spent liquor separated from the wet biomass during the pressing,

4) the steam explosion zone comprising a screw for transferring the biomass through the following successive zones:
a biomass cooking zone provided with a line for conveying the pressed biomass resulting from the second transfer zone and a steam injection line,
an expansion zone for expanding the biomass resulting from the cooking zone,
a separation zone for separating the steam from the biomass,

5) an acid liquor preparation zone provided
with a line conveying the spent liquor drawn off from the second transfer zone to the steam explosion zone and/or a line conveying the spen

Assignees

• Agronomique Inst Nat Rech
• Ifp Energies Now
• Argo Industries Rech Et Developpement
• Agro Industrie Recherches Developpement

Inventors

• Hudebine Damien
• Rousset Romain
• Carnnot Olivier

Classifications

• C08H8/00 Primary

  Macromolecular compounds derived from lignocellulosic materials {(pretreatment thereof B27N)} · CPC title

• C13K1/02 Primary

  obtained by saccharification of cellulosic materials (manufacture of fodder A23K10/32) · CPC title