Method and device for pelletizing unprocessed cellulosic fibrous material

• US 20070084385A1
• Filed: 09/28/2006
• Published: 04/19/2007
• Est. Priority Date: 09/28/2005
• Status: Abandoned Application

• Current Assignee: Cargill, Inc. (Agricultural Services Division)
• Original Assignee: Cargill, Inc. (Agricultural Services Division)
• Inventors: Curran, Michael, Lana, Pedro
• Application Number:
  US11/540,875
• Publication Number:
  US 20070084385A1
• Time in Patent Office: Days
• US Class Current: 110/219
• CPC Class Codes: B01J 2/12 in rotating drums
• CPC Class Codes: B30B 11/201 for extruding material
• CPC Class Codes: C10L 5/363 Pellets or granulates
• CPC Class Codes: C10L 5/366 Powders
• CPC Class Codes: C10L 5/44 on vegetable substances
• CPC Class Codes: C10L 5/48 on industrial residues and waste materials C10L5/403, C10L5/406 take precedence
• CPC Class Codes: F23G 2201/101 using indirect heat transfer
• CPC Class Codes: F23G 2201/602 different sizes
• CPC Class Codes: F23G 2900/50206 Pelletising waste before combustion
• CPC Class Codes: F23G 5/02 with pretreatment
• CPC Class Codes: F23G 5/04 drying
• CPC Class Codes: F23G 7/02 of bagasse, megasse or the like
• CPC Class Codes: Y02E 20/12 Heat utilisation in combustion or incineration of waste
• 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

The present invention relates to a method and a device for pelletizing unprocessed cellulosic fibrous material on an industrial scale, and in particular to the use of said unprocessed cellulosic fibrous material pellets as a combustible fuel product.

Claims

1. A method for drying a combustible cellulosic fibrous material, wherein said method comprises the step of drying of said combustible cellulosic fibrous material in a drying unit, wherein said drying unit comprises a heat source that indirectly provides heat to said combustible cellulosic fibrous material when drying said combustible cellulosic fibrous material.

2. The method according to claim 1, wherein said drying unit is a rotary dryer, in particular a spinning tube dryer (8).

3. The method according to claim 2, wherein said heat source comprises a system of tubes, in particular bundled tubes, conveying the heat source.

4. The method according to claim 3, wherein said heat source is saturated steam.

5. The method according to claim 2, wherein the heat source is applied at a temperature ranging from about 170 to about 185°

C. inside the tubes, resulting in temperatures ranging from about 135 to about 140°

C. on the external surfaces of the tubes in the drying unit.

6. The method according to any of claim 2, wherein the heat source is applied at a pressure of about 8.34 bar to about 9.81 bar (8.5 to 10 kgf/cm2) inside the tubes.

7. A method for pelletizing combustible cellulosic fibrous material, wherein said method comprises the following steps:

(a) providing and feeding of unprocessed combustible cellulosic fibrous material into said method,

(b) cleaning of said unprocessed combustible cellulosic fibrous material,

(c) drying of said cleaned unprocessed combustible cellulosic fibrous material,

(d) pelletization of said dried combustible cellulosic fibrous material, and

(e) sorting and drying of said pelletized combustible cellulosic fibrous material,

wherein the drying in step (c) comprises the step of drying of said combustible cellulosic fibrous material in a drying unit, wherein said drying unit comprises a heat source that indirectly provides heat to said combustible cellulosic fibrous material when drying said combustible cellulosic fibrous material.

8. The method according to claim 7, wherein in step (a) unprocessed combustible cellulosic fibrous material is continuously fed into the method while said material is loosened and flattened.

9. The method according to claim 7, wherein in step (b) ferrous material and impurities are removed from the unprocessed combustible cellulosic fibrous material.

10. The method according to claim 7, wherein in step (c) said drying step comprises applying a heat source that indirectly provides heat to said combustible cellulosic fibrous material when drying said combustible cellulosic fibrous material, wherein said heat source optionally comprises a system of tubes, in particular bundled tubes, conveying the heat source.

11. The method according to claim 10, wherein the heat source is applied at a temperature ranging from about 170 to about 185°

C. inside the tubes, resulting in temperatures ranging from about 135 to about 140°

C. on the external surfaces of the tubes in the drying unit.

12. The method according to claim 10, wherein the heat source is applied at a pressure of about 8.34 bar to about 9.81 bar (8.5 to 10 kgf/cm2) inside the tubes.

13. The method according to claim 10, wherein said combustible cellulosic fibrous material remains inside the tube dryer for about 12 minutes, at about 4 rpm using about 2 to about 3 metric tons of steam per hour.

14. The method according to claim 7, wherein in step (c) after the combustible cellulosic fibrous material leaves the tubular bundles, it is insufflated in counter flow with hot air by a duct coming from a heat radiator fed by saturated steam (VS).

15. The method according to claim 14, wherein in step (c) the hot and humid gases are removed on the opposite side of the entrance of the dryer by a duct with forced exhaust, and sent to a cyclone, or similar equipment, where the solid particles (powder) are separated and sent to be burned by the boiler.

16. The method according to claim 7, wherein in step (d) the dried combustible cellulosic fibrous material, with a humidity varying between about 13 to about 20% is continuously fed to the pelletizers, where the combustible cellulosic fibrous material receives an injection of saturated steam, and then enters the pelletizer'"'"'s pressing system.

17. The method according to claim 7, wherein after step (d) the combustible cellulosic fibrous material pellets are removed from the pelletizers, in particular by a variable-speed cleated or similar type conveyor belt.

18. The method according to claim 7, wherein in step (e) the combustible cellulosic fibrous material pellets are sorted according to their size, and/or in step (e) any rejected material at the sifter, together with any excess with excess dried combustible cellulosic fibrous material from the feeding conveyor belt is returned to the feed box to be reused in said method.

19. The method according to claim 7, wherein in step (e) the combustible cellulosic fibrous material pellets are cooled down to room temperature of about 20 to about 40°

C.

20. The method according to claim 7, wherein in step (f) the final combustible cellulosic fibrous material pellets, having a humidity ranging from about 9 to about 13% and a density between about 0.55 to about 0.60 g/cm³ are advanced to a storage system.

21. The method according to claims 7, further comprising storing of the dried combustible cellulosic fibrous material pellets in step (f).

22. The method according to claim 7, wherein said method is a fully automated and/or continuous method.

23. The method according to claim 7, wherein said combustible cellulosic fibrous material is selected from at least one of paper mill sludge, wood chips, paper fiber, cherry pits, olive pits, sugar-cane bagasse, sweet sorghum bagasse, grass clippings, and fur trees, and combinations thereof.

24. A device for converting unprocessed combustible cellulosic fibrous material into combustible compressed cellulosic fibrous material pellets by a method for pelletizing combustible cellulosic fibrous material, wherein said method comprises the following steps:

(a) providing and feeding of unprocessed combustible cellulosic fibrous material into said method,

(b) cleaning of said unprocessed combustible cellulosic fibrous material,

(c) drying of said cleaned unprocessed combustible cellulosic fibrous material,

(d) pelletization of said dried combustible cellulosic fibrous material, and

(e) sorting and drying of said pelletized combustible cellulosic fibrous material,

wherein the drying in step (c) comprises the step of drying of said combustible cellulosic fibrous material in a drying unit, wherein said drying unit comprises a heat source that indirectly provides heat to said combustible cellulosic fibrous material when drying said combustible cellulosic fibrous material,

wherein said device comprises a drying unit for drying of said combustible cellulosic fibrous material, wherein said drying unit comprises a heat source that indirectly provides heat to said combustible cellulosic fibrous material when drying said combustible cellulosic fibrous material.

25. A device for converting unprocessed combustible cellulosic fibrous material into combustible compressed cellulosic fibrous material pellets by a method for pelletizing combustible cellulosic fibrous material, wherein said method comprises the following steps:

(a) providing and feeding of unprocessed combustible cellulosic fibrous material into said method,

(b) cleaning of said unprocessed combustible cellulosic fibrous material,

(c) drying of said cleaned unprocessed combustible cellulosic fibrous material,

(d) pelletization of said dried combustible cellulosic fibrous material, and

(e) sorting and drying of said pelletized combustible cellulosic fibrous material,

wherein the drying in step (c) comprises the step of drying of said combustible cellulosic fibrous material in a drying unit, wherein said drying unit comprises a heat source that indirectly provides heat to said combustible cellulosic fibrous material when drying said combustible cellulosic fibrous material,

wherein said device comprises;

(a) a continuous feeding unit,

(b) a cleaning unit,

(c) a drying unit,

(d) a pelletization unit, and

(e) a sorting and second drying unit, and, optionally

(f) a storing unit.

26. The device according to claim 25, wherein unit (a) comprises a cleated or similar type conveyor belt, a feed box, and a sprayer.

27. The device according to claim 25, wherein said feed box can hold a 15-minute supply and has a rectangular flat-wall, a flat-bottom, and a cleated or similar type conveyor belt.

28. The device according to any of claim 25, wherein unit (b) comprises a cleated or similar type conveyor belt, an electromagnet, and a di-stone.

29. The device according to claim 28, wherein said electromagnet has a minimum magnetic capacity of about 1500 gauss, and said di-stone is a rotating machine consisting of about 5 to 8 perpendicular axes with star-shaped knives that counter-rotate.

30. The device according to claim 25, wherein unit (c) comprises a cleated or similar type conveyor belt, a spinning tube dryer, an insufflating system, and an exhaust system featuring cyclones.

31. The device according to claim 30, wherein said spinning tube dryer is fitted with deflectors positioned at about 45°

attached to the tube bundles, and the minimum spacing between the tubes is about 75 mm.

32. The device according to claim 25, wherein unit (d) comprises a cleated or similar type conveyor belt, sloping spouts, conditioner of the pelletizer, the pelletizers, and a variable-speed cleated or similar type conveyor belt (13).

33. The device according to claim 32, wherein said sloping spouts have adjustable gates and magnetic plates, said conditioner is a spinning cylindrical metal box with a diameter of about 450 mm, fitted with wings and driven by a motor of about 5 hp, and said pelletizer comprises a pressing system, a cast-steel case, holding the primary shafts, the hollow mold shafts, the compacting rollers and the motor itself, whereas the main shaft fixes the two compacting rollers and the scarpers.

34. The device according to claim 33, wherein said compacting roller having a diameter ranging from about 140 mm to about 220 mm, an eccentric shaft, a device with adjusting regulators and a metal shield pressing, having a thickness ranging from about 15 mm to about 40 mm and grooves about 2 to about 5 mm deep and about 2 to about 5 mm wide, and spaced about 8 to about 12 mm apart.

35. The device according to claim 34, wherein said pelletizer'"'"'s pressing system has a mold rotating at about 360 rpm, two pressing rollers, regulators and is driven by a motor of about 125 hp at about 1750 rpm.

36. The device according to claim 35, wherein said mold is fixed at the hollow rotating shaft, driven by gears and an electric motor with power varying from about 100 hp to 400 hp, at about 220 rpm to 420 rpm, is a metal ring with a flange for fixing on the hollow shaft and a surface with various holes, wheraes these holes can be of various sizes, and comprises a mold diameter of about 520 to 820 mm, a diameter of the mold holes of about 4.76 mm to about 19.05 mm ( 3/16″

to ¾

″

), a width of the track of the molds of about 100 to 220 mm, and a number of holes in the molds of about 860-4600 holes.

37. The device according to claim 25, wherein unit (e) comprises a variable-speed cleated or similar type conveyor belt, a vibrating sifter, a cooler with a cleated conveyor belt with a perforated screen, and an exhaust system with a cyclone.

38. The device according to claim 25, further comprising a storing unit (f)

39. The device according to claim 38, wherein unit (f) comprises a cleated or similar type conveyor belt, big bags or silos.

40. The device according to claim 25, wherein unit (d) and unit (e) are connected to unit (b) via a cleated or similar type conveyor belt.

41. The device according to claim 25, wherein said units are integrated into one system.

42. A pelletized combustible cellulosic fibrous material, obtainable by a method for pelletizing combustible cellulosic fibrous material, wherein said method comprises the following steps:

(a) providing and feeding of unprocessed combustible cellulosic fibrous material into said method,

(b) cleaning of said unprocessed combustible cellulosic fibrous material,

(c) drying of said cleaned unprocessed combustible cellulosic fibrous material,

(d) pelletization of said dried combustible cellulosic fibrous material, and

(e) sorting and drying of said pelletized combustible cellulosic fibrous material,

wherein the drying in step (c) comprises the step of drying of said combustible cellulosic fibrous material in a drying unit, wherein said drying unit comprises a heat source that indirectly provides heat to said combustible cellulosic fibrous material when drying said combustible cellulosic fibrous material.

43. The pelletized combustible cellulosic fibrous material according to claim 42, wherein said material has an upper calorific content of about 4,500 to about 5,500 kcal/kg, a lower calorific content of about 3,500 to about 4,500 kcal/kg, a density of about 500 to about 600 kg dry matter/m³, and a humidity of about 10% to about 15%.

44. The pelletized combustible cellulosic fibrous material according to claim 42, wherein said material is further blended with coal.

45. The pelletized combustible cellulosic fibrous material according to claim 42, wherein said pelletized combustible cellulosic fibrous material is selected from pellets of at least one of paper mill sludge, wood chips, paper fiber, cherry pits, olive pits, sugar-cane bagasse, sweet sorghum bagasse, grass clippings, and fur trees, and combinations thereof.

46. A method for generating energy and/or biofuel, comprising the use of a pelletized combustible cellulosic fibrous material, obtainable by a method for pelletizing combustible cellulosic fibrous material, wherein said method comprises the following steps:

(a) providing and feeding of unprocessed combustible cellulosic fibrous material into said method,

(b) cleaning of said unprocessed combustible cellulosic fibrous material,

(c) drying of said cleaned unprocessed combustible cellulosic fibrous material,

(d) pelletization of said dried combustible cellulosic fibrous material, and

(e) sorting and drying of said pelletized combustible cellulosic fibrous material,

wherein the drying in step (c) comprises the step of drying of said combustible cellulosic fibrous material in a drying unit, wherein said drying unit comprises a heat source that indirectly provides heat to said combustible cellulosic fibrous material when drying said combustible cellulosic fibrous material as a renewable biomass.

47. A method for producing a pelletized combustible cellulosic fibrous material comprising the use of a device for converting unprocessed combustible cellulosic fibrous material into combustible compressed cellulosic fibrous material pellets by a method for pelletizing combustible cellulosic fibrous material, wherein said method comprises the following steps:

(a) providing and feeding of unprocessed combustible cellulosic fibrous material into said method,

(b) cleaning of said unprocessed combustible cellulosic fibrous material,

(c) drying of said cleaned unprocessed combustible cellulosic fibrous material,

(d) pelletization of said dried combustible cellulosic fibrous material, and

(e) sorting and drying of said pelletized combustible cellulosic fibrous material,

wherein the drying in step (c) comprises the step of drying of said combustible cellulosic fibrous material in a drying unit, wherein said drying unit comprises a heat source that indirectly provides heat to said combustible cellulosic fibrous material when drying said combustible cellulosic fibrous material,

wherein said device comprises;

(a) a continuous feeding unit,

(b) a cleaning unit,

(c) a drying unit,

(d) a pelletization unit, and

(e) a sorting and second drying unit, and, optionally

(f) a storing unit.