Method and apparatus for controlling a fiber fractionation system

A method for controlling a fiber fractionation system for fractionating an input material into a long fraction (LF) stream comprising LF fibers and a short fraction (SF) stream comprising SF fibers, wherein the fiber fractionation system comprises an initial mass reject ratio (RRm), the method comprising:

• measuring an average LF fiber length at one or more locations post-fractionation;
• and
• maintaining the average LF fiber length within a target variability range by automatically altering:
• (i) a rotational speed of a rotor of the fiber fractionation system;
• and
• (ii) the initial RRm to a second RRm.

A method for controlling a fiber fractionation system for fractionating an input material into a long fraction (LF) stream comprising LF fibers and a short fraction (SF) stream comprising SF fibers, wherein the fiber fractionation system comprises an initial mass reject ratio (RRm), the method comprising:

• prior to fractionation, processing a pulp suspension comprising the LF and SF fibers with a turbulence generator;
• measuring an average LF fiber length at one or more locations post-fractionation;
• and
• maintaining the average LF fiber length within a target variability range by automatically altering at least one of:
• (i) a rotational speed of a rotor of the fiber fractionation system;
• or
• (ii) the initial RRm to a second RRm.

A method for controlling a fiber fractionation system for fractionating an input material into a long fraction (LF) stream comprising LF fibers and a short fraction (SF) stream comprising SF fibers, the method comprising:

• measuring an average LF fiber length at one or more locations post-fractionation;
• and
• maintaining the average LF fiber length within a target variability range by treating a pulp suspension comprising the LF and SF fibers with one or more chemicals to enhance binding of fines to the LF fibers, wherein the one or more chemicals are added prior to fractionation, during fractionation, or both, wherein the fiber fractionation system comprises an initial mass reject ratio (RRm) and wherein maintaining the average LF fiber length within the target variability range further comprises one or more of:
• automatically altering at least one of:
• (i) a rotational speed of a rotor of the fiber fractionation system;
• or
• (ii) the initial RRm to a second RRm;
• or
• applying, during fractionation, water to one or more portions of an interior surface of a fractionation screen of the fiber fractionation system.

A method for controlling a fiber fractionation system for fractionating an input material into a long fraction (LF) stream comprising LF fibers and a short fraction (SF) stream comprising SF fibers, the method comprising:

• measuring an average LF fiber length at one or more locations post-fractionation;
• and
• maintaining the average LF fiber length within a target variability range by treating a pulp suspension comprising the LF and SF fibers with one or more chemicals to reduce binding of fines to the LF fibers, wherein the one or more chemicals are added prior to fractionation, during fractionation, or both, wherein the fiber fractionation system comprises an initial mass reject ratio (RRm) and wherein maintaining the average LF fiber length within the target variability range further comprises one or more of:
• automatically altering at least one of:
• (i) a rotational speed of a rotor of the fiber fractionation system;
• or
• (ii) the initial RRm to a second RRm;
• or
• applying, during fractionation, water to one or more portions of an interior surface of a fractionation screen of the fiber fractionation system.

A method for controlling a fiber fractionation system for fractionating an input material into a long fraction (LF) stream comprising LF fibers and a short fraction (SF) stream comprising SF fibers, the method comprising:

• measuring an average LF fiber length at one or more locations post-fractionation;
• and
• maintaining the average LF fiber length within a target variability range by applying, during fractionation, water to one or more portions of an interior surface of a fractionation screen of the fiber fractionation system, wherein the fiber fractionation system comprises an initial mass reject ratio (RRm) and wherein maintaining the average LF fiber length within the target variability range further comprises one or more of:
• automatically altering at least one of:
• (i) a rotational speed of a rotor of the fiber fractionation system;
• or
• (ii) the initial RRm to a second RRm;
• treating a pulp suspension comprising the LF and SF fibers with one or more chemicals to enhance binding of fines to the LF fibers;
• or
• treating the pulp suspension comprising the LF and SF fibers with one or more chemicals to reduce binding of fines to the LF fibers,
• wherein the one or more chemicals are added prior to fractionation, during fractionation, or both.

A method for controlling a fiber fractionation system for fractionating an input material into a long fraction (LF) stream comprising LF fibers and a short fraction (SF) stream comprising SF fibers, the method comprising:

• measuring an average SF fiber length at one or more locations post-fractionation;
• and
• maintaining the average SF fiber length within a target variability range by automatically altering a rotational speed of a rotor of the fiber fractionation system, wherein:
• the fiber fractionation system comprises an initial mass reject ratio (RRm);
• and
• maintaining the average SF fiber length within the target variability range further comprises automatically altering the initial RRm to a second RRm.