Hydrolysis process

• US 4,908,067 A
• Filed: 01/21/1988
• Issued: 03/13/1990
• Est. Priority Date: 09/13/1984
• Status: Expired due to Term

• Current Assignee: Jack T.H. Just
• Original Assignee: Jack T.H. Just
• Inventors: Just, Jack T. H.
• Primary Examiner(s): Sneed, H. M. S.
• Assistant Examiner(s): Pak, Chung K.
• Application Number:
  US07/147,118
• Time in Patent Office: 782 Days
• Field of Search: 127/37, 127/1, 127/43, 127/45, 127/44, 127/53, 127/55, 530/500
• US Class Current: 127/37
• CPC Class Codes: C13K 1/02 obtained by saccharification of cellulosic materials manufacture of fodder A23K10/32
• CPC Class Codes: C13K 13/002 Xylose

Abstract

A continuous hydrolysis process for the hydrolysis of wood and wood derived products into sugars and other products, wherein woodchip or other feedstock is formed into a slurry which is acidified, pressurized and heated before being hydrolyzed in reactors J. Three heat exchangers L1, L2 and L3 form a closed circuit in which exchanger L2 recovers heat from the slurry, L1 returns heat to the slurry and L3 makes up lost heat. The slurry is cooled before pressure reduction by pressure reducing means N and separation of the solids and liquid. The cooling prevents flashing to steam of part of the liquid in the slurry so that the process is single phase where generation of steam is avoided. After separation the solids can proceed to further processing or to discharge as lignin as indicated by arrow B. The liquid can proceed to further processing or discharge as indicated by arrow D.

Claims

1. A process for the continuous hydrolysis of wood, comprising:

(I) continuously feeding said wood as a feedstock to a receiving of a presoak container;

(II) injecting a weak acid solution into the receiving means to presoak the feedstock;

(III) continuously feeding the acid presoak feedstock under pressure from the receiving means to a first reactor loop of a tubular reactor;

(IV) injecting water into the tubular reactor countercurrently to said feedstock to form a slurry;

(V) continuuously subjecting the slurry under pressure as it goes through several reactor loops in series;

(VI) heating each reactor loop with a first indirect heat exchanger to raise the temperature of the pressurized slurry therein to a temperature sufficient for hydrolysis of the slurry to occur;

(VII) cooling the pressurized slurry in each reactor loop with a second indirect heat exchanger to avoid the generation of vapour to ensure that the liquid portion of the slurry remains as a liquid;

(VIII) recovering heat from said second indirect heat exchanger and utilizing the heat recovered to supply at least part of the heat requirements of said first heat exchanger;

(IX) reducing with pressure reduction apparatus at an outlet of each reactor loop the pressure of the cooled slurry therein while maintaining the pressure in the reactor loop while the slurry is continuously discharged;

(X) separating the solid portion of the slurry using a separator;

(XI) recovering the solid portion containing lignin and passing it to the next reactor loop of the tubular reactor; and

(XII) recovering the liquid portion of the slurry which is sugar rich acid-hydrolysate and injecting a part of the liquid portion to the preceding reactor loop of the tubular reactor.

2. A process as claimed in claim 1 wherein a third indirect heat exchanger is provided in each closed reactor loop to supplement the heat requirement of said first heat exchanger.

3. A process for the continuous hydrolysis of cellulose, comprising:

(I) continuously feeding said cellulose as a feed stock to a receiving means of a presoak container;

(II) injecting a weak acid solution into the receiving means to presoak the feedstock;

(III) continuously feeding the acid presoak feedstock under pressure from the receiving means to a first reactor loop of a tubular reactor;

(IV) injecting water into the tubular reactor countercurrently to said feedstock to form a slurry;

(V) continuously subjecting the slurry under pressure as it goes through several reactor loops in series;

(VI) heating each reactor loop with a first indirect heat exchanger to raise the temperature of the pressurized slurry therein to a temperature sufficient for hydrolysis of the slurry to occur;

maintaining with its said first heat exchanger the temperature of the slurry in the process line for sufficient time for leaching of the slurry to occur;

(VII) cooling the pressurized slurry in each reactor loop with a second indirect heat exchanger to avoid the generation of vapour to ensure that the liquid portion of the slurry remains as a liquid;

(VII) recovering heat from said secnd indirect heat exchanger and u tilizing the heat recovered to supply at least part of the heat requirements of said first heat exchanger;

(VIII) reducing with pressure reduction apparatus at an outlet of each reactor loop the pressure of the cooled slurry therein while maintaining the pressure in the reactor loop while the slurry is continuously discharged;

(IX) separating the solid portion of the slurry using a separator;

(X) recovering the solid portion containing lignin and passing it to the next reactor loop of the tubular reactor; and

(XI) recovering the liquid portion of the slurry which is sugar rich acid-hydrolysate and injecting a part of the liquid portion to the preceding reactor loop of the tubular reactor.

4. A process for the continuous hydrolysis of wood, comprising:

(I) continuously feeding said wood as a feedstock to a receiving means of a presoak container;

(II) injecting water into the receiving means to presoak the feedstock;

(III) continuously feeding the water presoak feedstock under pressure from the receiving means to a first reactor loop of a tubular reactor;

(IV) injecting additional water into the tubular reactor countercurrently to said feedstock to form a slurry;

(V) injecting a weak acid solution into the tubular reactor;

(VI) continuously subjecting the slurry under pressure as it goes through several reactor loops in series;

(VII) heating each reactor loop with a first indirect heat exchanger to raise the temperature of the pressurized slurry therein to a temperature sufficient for hydrolysis of the slurry to occur;

(VIII) cooling the pressurized slurry in each reactor loop with a second indirect heat exchanger to avoid the generation of vapour to ensure that the liquid portion of the slurry remains as a liquid;

(IX) recovering heat from said second indirect heat exchanger and utilizing the heat recovered to supply at least part of the heat requirements of said first heat exchanger;

(X) reducing with pressure reduction apparatus at an outlet of each reactor loop the pressure of the cooled sIurry therein while maintaining the pressure in the reactor loop while the slurry is continuously discharged;

(XII) separating the solid portion of the slurry using a separator;

(XII) recovering the solid portion containing lignin and passing it to the next reactor loop of the tubular reactor; and

(XIII) recovering the liquid portion of the slurry which is sugar rich acid-hydrolysate and injecting a part of the liquid portion to the preceding reactor loop of the tubular reactor.