Pretreatment process of a ligno-cellulosic feedstock

Patent metadata

Field	Value
Publication number	US-10316466-B2
Application number	US-201615548425-A
Country	US
Kind code	B2
Filing date	Jan 28, 2016
Priority date	Feb 9, 2015
Publication date	Jun 11, 2019
Grant date	Jun 11, 2019

Abstract

It is disclosed a process to transfer a ligno-cellulosic feedstock from a low pressure zone to a high pressure zone. A slurry the ligno-cellulosic feedstock is first provided, which is then subjected to a multi-step liquid removal process comprising draining by gravity at least a portion of the free liquid; removing a first portion of the capillary liquid in a low pressure zone by continuously compressing a stream of the ligno-cellulosic feedstock to reach a moisture content in a first target range; removing a second portion of the capillary liquid by shearing and compressing the ligno-cellulosic stream in a plug forming device, to form a ligno-cellulosic feedstock plug having a moisture content in a second target range at an outlet of the plug forming device connected to the high pressure zone. In the removal of the first portion of the capillary liquid, at least one first compression device continuously compresses the stream of the drained ligno-cellulosic feedstock to a first control pressure, while conveying the stream of the drained ligno-cellulosic feedstock in a flow direction of a belt filter press.

First claim

The invention claimed is:

1. A continuous pretreatment of a ligno-cellulosic feedstock having a starting liquid retention capability and a starting moisture content which is less than a first target range, the process comprising the steps of:
a. providing a slurry of the ligno-cellulosic feedstock;
b. draining by gravity at least a portion of a free liquid of the slurry to produce a drained ligno-cellulosic feedstock containing a capillary liquid;
c. removing a first portion of the capillary liquid in a low pressure zone operating at atmospheric pressure by compressing a stream of the drained ligno-cellulosic feedstock at a compression ratio in a range of greater than 1:1 to 12:1, to produce a dewatered ligno-cellulosic feedstock stream having a moisture content in the first target range which is from 65% to 85%;
d. removing a second portion of the capillary liquid from the dewatered ligno-cellulosic feedstock stream by shearing and compressing the dewatered ligno-cellulosic feedstock stream in a plug forming device, to form and advance a ligno-cellulosic feedstock plug into a high pressure reactor operating in the range of greater than 600 kPa to 4,000 kPa connected to an outlet of the plug forming device plug;
e. subjecting the ligno-cellulosic feedstock to a hydrothermal treatment in the presence of water in liquid or steam phase or a mixture thereof at a hydrothermal temperature in the range of 160° C. to 250° C. for a hydrothermal time in the range of 10 sec. to 2 hour to produce a pretreated lignocellulosic feedstock.

2. The process of claim 1 , wherein the process further comprises steam exploding the pretreated lignocellulosic feedstock.

3. The process of claim 1 , wherein providing the slurry of the ligno-cellulosic feedstock comprises the step of treating the ligno-cellulosic feedstock treatment in the presence of water in liquid or steam phase at a temperature between 60° C. and 160° C., and for a time sufficient to create a slurry comprising a free liquid and a treated ligno-cellulosic feedstock, wherein the treated ligno-cellulosic feedstock has a liquid retention capability which is greater than the starting liquid retention capability.

4. The process of claim 3 , wherein the treatment of the ligno-cellulosic feedstock is conducted for a time which is in a range selected from the group consisting of 5 minutes to 3 hours.

5. The process of claim 3 , wherein the lignocellulosic feedstock comprises carbohydrates and the percent amount of carbohydrates solubilized in the thermal treatment is less than 10 by weight.

6. The process of claim 1 , wherein providing the slurry of the ligno-cellulosic feedstock comprises the step of soaking the ligno-cellulosic feedstock in a soaking liquid comprising water a soaking temperature between 30° C. and 100° C., and for a soaking time sufficient to create a slurry comprising a free liquid and a soaked ligno-cellulosic feedstock without altering the starting liquid retention capability, wherein the soaked ligno-cellulosic feedstock has a moisture content which is greater than 80% of the starting liquid retention capability.

7. The process of claim 6 , wherein the ligno-cellulosic feedstock comprises a ligno-cellulosic component and non-ligno-cellulosic water soluble compounds, and the free liquid comprises water and water soluble species derived from the non ligno-cellulosic water soluble compounds.

8. The process of claim 6 , wherein the soaking temperature is in a range selected from the group consisting of 40° C. to 99° C.

9. The process of claim 6 , wherein the soaking time is in a range selected from the group consisting of 30 seconds to 300 minutes.

10. The process of claim 1 , wherein the stream of the drained ligno-cellulosic feedstock is continuously compressed to at least one control pressure.

11. The process of claim 10 , wherein at least one first compression device continuously compresses the stream of the drained ligno-cellulosic feedstock to a first control pressure, while conveying the stream of the drained ligno-cellulosic feedstock in a flow direction of a belt filter press.

12. The process of claim 10 , wherein the first control pressure is a value in a range of 100 kPa to 10,000 kPa.

13. The process of claim 10 , wherein there are more than one compression devices distributed along the flow direction, each having a control pressure.

14. The process of claim 13 , wherein the control pressure of the compression devices increases along the flowing direction.

15. The process of claim 1 , wherein the first target range is from 70% to 80.

16. The process of claim 1 , wherein the hydrothermal temperature of step f) is a value in a from 170° C. to 230° C.

17. The process of claim 1 , wherein the hydrothermal time of step f) is a value in a range consisting of from 30 seconds to 1 hour.

18. The process of claim 1 , wherein the ligno-cellulosic feedstock is a straw.

19. The process of claim 1 , wherein the ligno-cellulosic feedstock is selected from the group consisting of wheat straw, rice straw, barley straw, and bagasse.

Assignees

• Versalis Spa

Inventors

• Ghisolfi Guido
• Bonaldi Ettore

Classifications

• D21C9/18

  De-watering (de-watering in general F26B); {Elimination of cooking or pulp-treating liquors from the pulp}(D21C9/002, D21C9/02 take precedence; paper-making machines D21F; strainers in digesters D21C7/00; presses in general B30B) · CPC title

• D21C1/02 Primary

  with water or steam · CPC title

• D21B1/02 Primary

  Pretreatment of the raw materials by chemical or physical means (removal of bark B27L) · CPC title

• D21B1/36

  Explosive disintegration by sudden pressure reduction · CPC title

• Y02E50/10

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