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Method for increasing the accessibility of cellulose in lignocellulosic materials, particularly hardwoods agricultural residues and the like

  • US 4,461,648 A
  • Filed: 06/01/1981
  • Issued: 07/24/1984
  • Est. Priority Date: 07/11/1980
  • Status: Expired due to Term
First Claim
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1. An improved method for increasing the accessibility of cellulose in lignocellulosic materials, such as hardwoods, bagasse and the like, to rumen bacteria, enzymes, microorganisms and the like, characterized by an optimization of a range of cooking times (tc) which will respond to the actual pressure conditions in the reactor as they may change over time during a given cooking run and render the cellulose most open for attack by said microorganisms or enzymes, as measured by the rate or extent of their reaction, said method comprising the steps of:

  • (a) feeding lignocellulosic material, in a divided form, into a pressure reactor vessel; and

    (b) introducing pressurized steam into the vessel during a pressurization time phase so as to reach reactor pressures of between 250 and 1000 psig wherein said reactor pressures does follow a given time profile; and

    (c) cooking by maintaining the lignocellulosic material at said time variable pressures between 250 and 1000 psig for a total period of time (tc) in seconds, which includes the pressurization phase, wherein t3

    tc

    t4 and the given reactor pressure time profile is used to determine t3 and t4 for that given cook run since t3 is defined implicitly by ##EQU11## and t4 and defined implicitly by ##EQU12## wherein Ts is the temperature (°

    C.) of saturated steam, at the indicated reactor pressures and corresponds to the saturated steam temperature values along the indicated reactor pressure time profile, thereby also making Ts a given function of time (t); and

    (d) decompressing the cooked lignocellulosic material down to substantially atmospheric pressure at the end of said cooking time, tc.

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