Appeal No. 1998-1053
Application No. 07/974,832
estimating a current velocity of the jet of foamed
furnish leaving the headbox using the density and pressure
measurements
using neither direct measurement of flow velocity nor direct
measurement of flow volume flow rate of the jet; and
comparing the estimated current jet velocity with a
target velocity and controlling said feeding step to move the
estimated current velocity and the target velocity closer to
each other.
CLAIM 14
A method of controlling the velocity of a jet of foamed
furnish leaving a pressurized headbox of a paper or a tissue
making machine comprising the steps of:
operating a pump to provide a flow of foamed furnish;
measuring the density and the pressure of said flow of
foamed furnish and using resulting measurements to estimate an
atmospheric pressure air content;
delivering said flow of foamed furnish to a pressurized
headbox having a slice emitting a jet of said foamed furnish
and measuring the pressure of the foamed furnish in the
headbox;
estimating the current velocity of said jet of foamed
furnish using the estimated atmospheric pressure air content
and the measured pressure in the headbox using neither direct
measurement of flow velocity nor direct measurement of volume
flow rate of the jet; and
comparing the estimated current velocity of said jet of
foamed furnish with a target velocity and controlling said
pump to move the estimated and target velocities closer to
A-4
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