Apparatus for treating cellulosic materials

• US 6,176,176 B1
• Filed: 04/30/1998
• Issued: 01/23/2001
• Est. Priority Date: 04/30/1998
• Status: Expired due to Term

• Current Assignee: The Board of Trustees of Michigan State University (Michigan State University)
• Original Assignee: The Board of Trustees of Michigan State University (Michigan State University)
• Inventors: Dale, Bruce E., Weaver, Justin K.
• Primary Examiner(s): Hendricks, Keith D.
• Assistant Examiner(s): BECKER, DREW E
• Application Number:
  US09/070,576
• Time in Patent Office: 999 Days
• Field of Search: 994/67, 994/69, 994/70, 994/73, 994/77, 994/82, 994/83, 425/110, 425/113, 425/200, 425/208, 425/209, 425/DIG.16, 425/74
• US Class Current: 99/470
• CPC Class Codes: A23K 10/32 from hydrolysates of wood or straw
• CPC Class Codes: A23K 40/20 by moulding, e.g. making cakes or briquettes
• CPC Class Codes: A23K 40/25 by extrusion
• CPC Class Codes: A23K 50/15 containing substances which are metabolically converted to proteins, e.g. ammonium salts or urea
• CPC Class Codes: A23P 30/34 by extrusion-expansion
• CPC Class Codes: B29C 48/022 characterised by the choice of material
• CPC Class Codes: B29C 48/09 Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels
• CPC Class Codes: B29C 48/12 Articles with an irregular circumference when viewed in cross-section, e.g. window profiles
• CPC Class Codes: B29C 48/2564 Screw parts
• CPC Class Codes: B29C 48/58 provided with seal ring elements, i.e. elements of generally circular and tapered shape for preventing the back flow of the melt
• CPC Class Codes: B29K 2093/00 Use of natural resins, e.g. shellac, or derivatives thereof, as moulding material B29K2001/00, B29K2003/00, B29K2005/00, B29K2007/00 and B29K2089/00 take precedence
• CPC Class Codes: C12P 2201/00 Pretreatment of cellulosic or lignocellulosic material for subsequent enzymatic treatment or hydrolysis
• CPC Class Codes: Y10S 426/807 Poultry or ruminant feed

Abstract

A process and screw in barrel apparatus (10) for expanding cellulosic materials is described. The expanded cellulosic material is useful as an animal feed and a nutrient source for fermentation processes.

Claims

1. An apparatus for producing an explosively expanded lignocellulosic material which comprises:

(a) at least one rotatable screw mounted in a barrel of an extruder with opposed ends, a feed inlet for the lignocellulosic material to the screw through the barrel, and a feed outlet from the screw and the barrel, and heating and cooling means between the ends of the barrel;

(b) a supply tank containing liquid ammonia under pressure;

(c) a supply line with a pump leading to a liquid inlet into the barrel from the supply tank downstream of the feed inlet in a mixing zone containing kneading blocks to mix the ammonia and lignocellulosic material and to impede the liquid ammonia from flowing to the feed inlet, which supply line contains a check valve after the pump set to open at a pressure of the liquid ammonia to be delivered to the liquid inlet and to close at above the vapor pressure of the liquid ammonia;

wherein the liquid inlet to the screw through the barrel is intermediate the ends for supplying the liquid ammonia from the supply tank, whereby the liquid ammonia is fed to the screw under pressure and maintained under pressure in the barrel as liquefied ammonia so that a lignocellulosic material containing the liquid ammonia is expanded explosively by change of the liquid to a gas upon removal of the lignocellulosic material from the barrel through an opening in a die means at the feed outlet by the rotation of the screw with at least one heating element in the die means adapted to heat the die means to expand the liquid ammonia explosively upon removal from the die means, wherein the extruder, opening in the die means and the heating element in the die means cooperate such that the expanded lignocellulosic material has an increase in total available sugar content over the lignocellulosic material prior to being introduced into the feed inlet and wherein a screw element adjacent to the die means at the feed outlet is tapered inward towards a longitudinal axis of the screw to force the lignocellulosic material with the liquid ammonia out the die means.

2. The apparatus of claim 1 wherein the die means has an opening which is inwardly tapered such that the lignocellulosic material is compressed by the die means before its removal.

3. The apparatus of claim 1 or 2 wherein the barrel is provided with spaced apart heating and cooling elements as the heating and cooling means along its length which maintain the lignocellulosic material at a temperature which facilitates expansion of the cellulosic material upon removal from the die means.

4. A system for explosively expanding a lignocellulosic material using liquid ammonia which comprises:

(a) an apparatus with at least one rotatable screw mounted in a barrel of an extruder with opposed ends, a feed inlet to the screw through the barrel for the lignocellulosic material at one end which is upstream, and a feed outlet from the screw and the barrel for the lignocellulosic material wherein a screw element of the screw adjacent to the feed outlet is tapered inward towards a longitudinal axis of the screw and wherein the screw element has screw flights and one of the flights adjacent to the feed outlet provides the tapered end, and heating and cooling means between the ends of the barrel, a liquid inlet for the liquid ammonia to the screw through the barrel intermediate the ends, whereby the liquid is fed to the screw under pressure through the liquid inlet and maintained under pressure in the barrel as liquid ammonia so that a lignocellulosic material containing the liquid ammonia is expanded explosively by change of the liquid to a gas upon removal of the lignocellulosic material from the barrel through an opening in a heated die means at the feed outlet by the rotation of the screw with at least one heating element in the die means which heats the die means to expand the liquid explosively;

(b) a liquid supply tank containing liquid ammonia under pressure and connected to the inlet of the liquid inlet;

(c) a supply line with a pump leading to the liquid inlet into the barrel from the supply tank downstream of the feed inlet in a mixing zone containing kneading blocks to mix the ammonia and lignocellulosic material and to impede the liquid ammonia from flowing to the feed inlet, which supply line contains a check valve after the pump set to open at a pressure of the liquid ammonia to be delivered to the liquid inlet and to close at above the vapor pressure of the liquid ammonia;

(d) a confined space in which the system is placed separate from operators of the apparatus and is continuously purged of the ammonia released from the explosively expanded lignocellulosic material; and

(e) gas removal means adjacent the die means in the confined space for removing ammonia which is released from the liquid ammonia and lignocellulosic material upon explosive expansion of the lignocellulosic material outside of the die means, wherein the extruder, the opening in the die means and the heating by the heating element cooperate such, that the explosively expanded lignocellulosic material has an increased total available sugar content over the lignocellulosic material supplied to the feed inlet as a result of the explosive expansion of the liquid ammonia to a gas.

5. The system of claim 4 wherein the die means has an opening which is inwardly tapered such that the lignocellulosic material is compressed by the die means before the removal of the lignocellulosic material from the die means.

6. The system of claim 4 or 5 wherein the barrel is provided with heating and cooling elements as the heating and cooling means which maintain the lignocellulosic material at a temperature which facilitates expansion of the lignocellulosic material by change of the liquid to a gas upon removal of the lignocellulosic material from the die means.

7. An apparatus for the continuous explosive expansion of a lignocellulosic material, comprising:

(a) at least one rotatable screw mounted in a barrel of an extruder with opposed ends having an inlet and heating and cooling means between the ends of the barrel, and a feed outlet, and wherein configuration of the screw at the outlet end is tapered with camel screw elements and the screw further comprises forward transport screw elements upstream and downstream of kneading block elements which provide a mixing zone intermediate to ends of the screw;

(b) means providing a lignocellulosic material to the inlet;

(c) a fluid inlet intermediate the ends of the barrel providing liquid ammonia to the lignocellulosic material in the mixing zone under a pressure below the vapor pressure of the liquid ammonia wherein the mixing zone mixes the liquid ammonia with the lignocellulosic material and to impede the liquid ammonia from flowing to the feed inlet;

(d) a heated die means at the feed outlet with a heating element in the die means wherein the outlet to the die means defines an opening that is 60% of the surface area of the opening at the inlet to the die means;

wherein the extruder, the mixing zone, configuration of the opening in the die means, the heating element in the die means, and configuration of the screw at the outlet end cooperate to provide sufficient pressure to maintain the liquid ammonia as a liquid such that when the mixture of lignocellulosic material and liquid ammonia is forced out of the extruder by the configuration of the screw at the outlet end, the liquid ammonia turns to a gas which explosively expands the lignocellulosic material thereby increasing total available sugar content of the lignocellulosic material over the lignocellulosic material prior to being introduced into the feed inlet.