PROCESSES FOR PRODUCING HIGH-VISCOSITY COMPOUNDS AS RHEOLOGY MODIFIERS, AND COMPOSITIONS PRODUCED THEREFROM
A process is provided for producing a biomass-derived rheology modifier, comprising: providing a pretreated feedstock comprising cellulose-rich solids; refining the cellulose-rich solids in a first high-intensity refining unit, generating refined cellulose solids; gelling the refined cellulose solids in a second high-intensity refining unit, thereby generating gelled cellulose solids; and homogenizing the gelled cellulose solids in a high-shear homogenizer, thereby generating a biomass-derived rheology modifier. The pretreated feedstock may include kraft pulp, sulfite pulp, AVAP® pulp, soda pulp, mechanical pulp, thermomechanical pulp, and/or chemimechanical pulp, derived from wood or lignocellulosic biomass. The pretreated feedstock may be GP3+® pulp, obtained from steam or hot-water extraction of lignocellulosic biomass. These rheology modifiers may be utilized in a wide variety of applications, including water-based or oil-based hydraulic fracturing fluid formulations, as gelling agents. These rheology modifiers are biodegradable, and their production does not directly involve chemicals other than biomass and water.
1 . A process for producing a biomass-derived rheology modifier from cellulosic biomass, said process comprising:
(a) providing a feedstock comprising cellulosic biomass;
(b) digesting said feedstock with a reaction solution including steam and/or hot water in a digestor under effective reaction conditions to produce a digested stream containing cellulose-rich solids, hemicellulose oligomers, and lignin;
(c) refining said cellulose-rich solids in a first high-intensity refining unit, thereby generating refined cellulose solids;
(d) washing said refined cellulose solids following step (c), and/or washing said digested stream prior to step (c) followed by said refining, thereby generating washed refined cellulose solids;
(e) gelling said washed refined cellulose solids in a second high-intensity refining unit, thereby generating gelled cellulose solids; and
(f) homogenizing said gelled cellulose solids in a high-shear homogenizer, thereby generating a biomass-derived rheology modifier.
2 . The process of claim 1 , said process further comprising wet or dry cleaning said feedstock prior to step (b).
3 . The process of claim 1 , wherein step (b) is conducted at a digestion temperature from about 140° C. to about 210° C.
4 . The process of claim 1 , wherein step (b) is conducted for a digestion time from about 5 minutes to about 45 minutes.
5 . The process of claim 1 , wherein step (b) is conducted at a liquid/solid weight ratio from about 2 to about 6.
6 . The process of claim 1 , said process further comprising a hot-blow pressure reduction of said digested stream, following step (b).
7 . The process of claim 1 , said process further comprising a cold-blow pressure reduction of said digested stream, following step (b).
8 . The process of claim 1 , wherein said first high-intensity refining unit includes disks.
9 . The process of claim 1 , wherein said first high-intensity refining unit includes a conical plate.
10 . The process of claim 1 , wherein said first high-intensity refining unit transfers energy to said cellulose-rich solids in an amount from about 20 kW/ton to about 200 kW/ton (bone-dry basis).
11 . The process of claim 1 , wherein washing in step (d) is conducted at a temperature from about 18° C. to about 95° C.
12 . The process of claim 1 , wherein washing in step (d) utilizes a pressurized screw press.
13 . The process of claim 1 , wherein said second high-intensity refining unit includes disks.
14 . The process of claim 1 , wherein said second high-intensity refining unit includes a conical plate.
15 . The process of claim 1 , wherein said second high-intensity refining unit transfers energy to said washed refined cellulose solids in an amount from about 20 kW/ton to about 200 kW/ton (bone-dry basis).
16 . The process of claim 1 , wherein said high-shear homogenizer transfers a shear force equivalent to a shear force produced under a pressure from about 10,000 psig to about 25,000 psig.
17 . The process of claim 1 , wherein step (e) is conducted at a different location than steps (a)-(d) and/or step (f) is conducted at a different location than steps (a)-(e).
18 . The process of claim 1 , wherein said biomass-derived rheology modifier is characterized by a particle size from about 5 microns to about 100 microns.
19 . A process for producing a biomass-derived rheology modifier from cellulosic biomass, said process comprising:
(a) providing a pretreated feedstock comprising cellulose-rich solids;
(b) refining said cellulose-rich solids in a first high-intensity refining unit, thereby generating refined cellulose solids;
(c) optionally washing said refined cellulose solids following step (b), and/or optionally washing said digested stream prior to step (b) followed by said refining, thereby generating washed refined cellulose solids;
(d) gelling said washed refined cellulose solids in a second high-intensity refining unit, thereby generating gelled cellulose solids; and
(e) homogenizing said gelled cellulose solids in a high-shear homogenizer, thereby generating a biomass-derived rheology modifier.
20 . The process of claim 19 , wherein said pretreated feedstock is pulp derived from wood or lignocellulosic biomass.