METHOD AND APPARATUS FOR CONVEYING A CELLULOSIC FEEDSTOCK

• US 20100186736A1
• Filed: 01/28/2009
• Published: 07/29/2010
• Est. Priority Date: 01/23/2009
• Status: Active Grant

• Current Assignee: Abengoa Bioenergy New Technologies, LLC (Abengoa SA)
• Original Assignee: Sunopta Bioprocess Inc. (Lallemand Inc.)
• Inventors: Hillier, Sunalie N., Burke, Murray J.
• Granted Patent: US 9,004,742 B2
• Time in Patent Office: Days
• US Class Current: 127/1
• CPC Class Codes: B65D 88/54 characterised by means facilitating filling or emptying filling or emptying features for flexible large containers B65B69/0075; construction or shape of discharge section of hoppers B65D88/28; gates or closures B65D90/54; filling or emptying bunkers, hoppers, or like containers B65G65/30
• CPC Class Codes: B65G 33/18 with multiple screws in parallel arrangements , e.g. concentric
• CPC Class Codes: B65G 65/46 using screw conveyors
• CPC Class Codes: C08H 8/00 Macromolecular compounds derived from lignocellulosic materials pretreatment thereof B27N
• CPC Class Codes: C13K 1/02 obtained by saccharification of cellulosic materials manufacture of fodder A23K10/32
• CPC Class Codes: D21C 1/00 Pretreatment of the finely-divided materials before digesting of waste paper D21C5/02
• CPC Class Codes: D21C 11/0007 Recovery of by-products, i.e. compounds other than those necessary for pulping, for multiple uses or not otherwise provided for volatile compounds obtained by decomposition of spent liquors in order to regenerate them D21C11/125; compounds obtained by fractionating the liquors in order to regenerate them D21C11/0042
• CPC Class Codes: D21C 9/08 Removal of fats, resins, pitch or waxes; Chemical or physical purification, i.e. refining, of crude cellulose by removing non-cellulosic contaminants, optionally combined with bleaching fats, waxes C11B; natural resins C09F1/00; hemicellulose C08B37/14; purification by mechanical means D21D5/00
• CPC Class Codes: D21D 5/28 Tanks for storing or agitating pulp
• CPC Class Codes: Y02E 50/10 Biofuels, e.g. bio-diesel

Abstract

A method and apparatus for conveying a cellulosic feedstock are disclosed. The apparatus, such as a holding tank, has a passage. At the outlet to the passage, a conveyance member is provided to convey the cellulosic feedstock laterally across the outlet. The conveyance member, e.g., at least one screw conveyor, may have a variable pitch along its length. The method comprises passing the cellulosic feedstock through an impregnation chamber to an outlet of the impregnation chamber; passing the cellulosic feedstock from the outlet of the impregnation chamber to an inlet of a holding tank; passing the cellulosic feedstock downwardly through the holding tank; maintaining a generally constant residence time in the holding tank; and subsequently subjecting the cellulosic feedstock to a hydrolysis process.

Claims

1. A holding tank apparatus for preparing a cellulosic feedstock, comprising:

(a) at least one sidewall defining a volume having an upper portion and a lower portion;

(b) at least one inlet adjacent the upper portion;

(c) at least a one outlet adjacent the lower portion, at an elevation below the inlet; and

,

(d) at least one screw conveyor conveying the cellulosic feedstock laterally across the outlet, the at least one screw conveyor having a variable pitch along its length.

2. The apparatus of claim 1, wherein the at least one screw conveyor has a first end and a second end, and the pitch at the first end differs from the pitch at the second end.

3. The apparatus of claim 2, wherein the at least one screw conveyor comprises a first region having a first range of pitch, and a second region having a second range of pitch.

4. The apparatus of claim 3, further comprising an intermediate region between the first region and the second region, the intermediate region having a third range of pitch between the first range of pitch and the second range of pitch.

5. The apparatus of claim 1, wherein the at least one screw conveyor has a first end and a second end, and the pitch decreases from the first end to the second end.

6. The apparatus of claim 5, wherein the pitch varies at a constant rate between the first end and the second end.

7. The apparatus of claim 5, wherein the outlet defines a plurality of portions and the pitch varies such that approximate equal portions of feedstock are withdrawn from each portion of the outlet.

8. The apparatus of claim 1, wherein the at least one screw conveyor comprises a plurality of screw conveyors and at least one of the screw conveyors conveys the cellulosic feedstock in a first direction and at least one of the screw conveyors conveys the cellulosic feedstock in a second direction

9. The apparatus of claim 8, wherein the first direction and the second direction are substantially opposite.

10. The apparatus of claim 1, wherein the at least one screw conveyor comprises a plurality of screw conveyors and at least two adjacent two screw conveyors have a length and convey the cellulosic feedstock in a first direction and the pitch of the screw conveyors at any location along the length of the screw conveyors is essentially the same.

11. The apparatus of claim 9, wherein the apparatus comprises a plurality of screw conveyors having a length, wherein a first pair of the screw conveyors conveys cellulosic feedstock in the first direction, and a second pair of the screw conveyors conveys cellulosic feedstock in the second direction.

12. The apparatus of claim 9, wherein the pitch of the first pair of screw conveyors at any location along the length is essentially the same and the pitch of the second pair of screw conveyors at any location along the length is essentially the same.

13. The apparatus of claim 9, wherein the pitch of the first pair of screw conveyors conveying cellulosic feedstock in the first direction is a mirror image of the pitch of the second pair of the screw conveyors conveying cellulosic feedstock in the second direction.

14. The apparatus of claim 9, wherein the first pair of screw conveyors is rotatable in a first direction, and the second pair of screw conveyors is rotatable in the opposite direction.

15. The apparatus of claim 1, wherein the at least one screw conveyor extends across all of the outlet.

16. The apparatus of claim 1, further comprising a heating jacket provided on at least a portion of the apparatus.

17. The apparatus of claim 1, wherein the lower portion has a greater cross sectional area then the upper portion.

18. The apparatus of claim 1, wherein the sidewalls comprise a first sidewall and a second sidewall opposed to the first sidewall, the first and second sidewalls diverging relative to each other from the upper portion to the lower portion.

19. The apparatus of claim 18, wherein the sidewalls comprise a third sidewall and a fourth sidewall opposed to the third sidewall, the third and fourth sidewalls extending between the first and second sidewalls, the third and fourth sidewalls diverging relative to each other from the upper portion to the lower portion.

20. A method of preparing a cellulosic feedstock for ethanol production, comprising:

(a) passing the cellulosic feedstock through an impregnation chamber to an outlet of the impregnation chamber;

(b) passing the cellulosic feedstock from the outlet of the impregnation chamber to an inlet of a holding tank, the holding tank having an outlet;

(c) passing the cellulosic feedstock downwardly through the holding tank;

(d) maintaining a generally constant residence time in the holding tank; and

(e) subsequently subjecting the cellulosic feedstock to a downstream hydrolysis process.

21. The method of claim 20, further comprising maintaining a temperature in the holding tank between about 50°

Celsius and about 75°

Celsius.

22. The method of claim 20, further comprising maintaining a variance of the residence time of each portion of the amount of up to 5 minutes.

23. The method of claim 20, maintaining a residence time in the holding tank from about 10 to about 30 minutes.

24. The method of claim 20, further comprising conveying the cellulosic feedstock laterally across an outlet of the holding tank.

25. The method of claim 24, wherein the cellulosic feedstock is actively withdrawn from essentially the entirety of the outlet.

26. The method of claim 24, wherein a generally equal amount of cellulosic feedstock is withdrawn from each portion of the outlet.

27. The method of claim 24, wherein the cellulosic feedstock is conveyed in at least two different lateral directions.

28. The method of claim 20, wherein a screw conveyor having different pitches is utilized to convey the cellulosic feedstock laterally across the outlet of the holding tank.