Appeal No. 1998-1053
Application No. 07/974,832
and pressure of the foamed furnish at closely adjacent
locations between said pump and said headbox;
measuring a parameter directly determinative of the
pressure of the foamed furnish at a location in said headbox;
estimating a current velocity of the jet based
substantially exclusively upon: said measurments determinative
of density and pressure; the density of the liquid phase; and
the difference in height between said jet and said location in
said headbox at which said parameter determinative of the
pressure of the foamed furnish in the headbox is measured;
providing a target velocity of the jet;
comparing the estimated and target jet velocities to
derive a control signal; and
utilizing the control signal to control the speed of the
positive displacement pump to vary the estimated jet velocity
to the target velocity.
CLAIM 29
A method of regulating a jet of foamed furnish leaving a
pressurized hydraulic headbox of a paper or a tissue making
machine having a moving foraminous support comprising the
steps of:
feeding foamed furninsh to a pressurized hydraulic
headbox to form a jet of said furnish to leave the headbox;
providing a parameter determinative of the velocity of
the moving foraminous support;
measuring parameters directly determinative of the
density and pressure of the foamed furnish fed to the headbox
and the pressure of the foamed furninsh in the headbox to
A-5
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