PSE 322 MIDTERM REVIEW QUESTIONS & ANSWERS
Non-integrated mill - Answers :Pulp is purchased in the form of dry bales.
These mills utilize a pulper.
Thick stock - Answers :Slurries with consistency of 3-5%.
Refining - Answers :An early technology of this mechanism is the Hollander beater,
which is oval in shape.
Repeated passes through a beating operation tend to make the fibers more flexible and
comfortable. This increases the area of adhesion (RBA) between fibers.
Blend chest - Answers :The location in which papermakers combine different streams of
stock into the system. Refining of each type of fiber is done before this location.
Machine Chest - Answers :Acts as a buffer capacity in the system. Provides a reservoir
of stock so that papermakers can make quick adjustments in the rate at which stock is
pumped towards the paper machine.
Freeness - Answers :A measure of the rate at which water drains from fiber in the
forming process.
Allows papermakers to achieve a better combo of strength properties at a given level of
freeness. - Answers :What is the purpose of separate refining?
Tickle refiners - Answers :By having one or more of these relatively late in the process,
papermakers can make quick adjustments and begin to see the results of such
adjustments a few minutes later.
The refining plates and general design of these are often selected to give a relatively
harsh, cutting action.
Increase in load and decrease in space between refining plates = decrease in freeness
and fiber length.
Stuff box - Answers :Provides a constant head so that the flow of thick-stock furnish to
the paper machine can be accurately controlled with a valve farther downstream.
Excess furnish is recirculated back into the machine chest. Often the last point where a
chemical can be added as a stream coming out of a simple hose at ambient pressure.
Stock valve - Answers :A papermakers primary tool for adjusting the basis weight of
paper. Controls the flow of thick stock to the paper machine.
A constant head
A steady, known value consistency
An accurate measurement of the total flow - Answers :Steady, accurate control of thick
stock flow requires 3 things:
,Mag meter - Answers :Magnetic flow analyzer
Obtains an accurate measure of total flow
After screening. This point is often positioned close enough after the pressure screens
so that it can still take advantage of the turbulent eddies generated by that operation. -
Answers :When is the last chance to add a chemical?
Ring header - Answers :Utilized to add chemical at four different points around the
circumference of the stock line. Often used for retention aid.
Injection quill - Answers :A type of pipe arrangement that discharges the additive near to
the center of flow within the stock line.
Approach Flow - Answers :Conveys the stock to the paper machine headbox, and at the
same time, spread the flow so that it matches the width of the paper machine.
Intake manifold - Answers :Where the flow is spread to the width of the paper machine.
On older paper machines this may consist of a series of dividing pipes.
Now it consists of a tapering header with tubes coming off from it at a right angle.
To knock down foam and prevent accumulation of deposits at the water line. - Answers
:Why are showers placed within air-padded headboxes?
Action - Answers :A moderate level of _______ tends to increase the rate of drainage
and produce a less flocky sheet. If it is too severe, blemishes can occur in the paper,
sometimes leading to web breaks.
Deculator - Answers :A deaeration system.
This unit applies a partial vacuum to the furnish, causing release of dissolved gases.
Minimizes some of the problems caused by dissolved or entrained air. These problems
can include pinholes in the paper, circular marks on the paper surface, and a significant
reduction in drainage rate.
Save-all - Answers :When excess white water leaves the primary circuit, the overflow
stream is directed to this device to avoid wasting all of the fine solids.
save - all . In modern paper mills it is common to find disc filters being used as these.
Sweetener - Answers :It is conventional practice to add a moderate level of pulp fibers
as this to help filter the fine material, and avoid its loss as effluent. Many paper machine
systems employ broke stock for this purpose.
Broke - Answers :Defined as repulped furnish; it tends to vary in unpredictable ways
due to paper breaks, grade changes, coating operations, and the fact that it can be
generated at different points in the papermaking process.
Hydrodynamic shear
, On a typical Fourdrinier, the pressure screens achieve some of the highest shear stress
values. - Answers :A change in velocity of fluid with distance, multiplied by a coefficient
of viscosity.
One had to consider this variable when adding chemicals to a process.
D.
especially in the case of an air-padded headbox
But hydraulic headboxes usually can be expected to impart higher levels of
hydrodynamic shear than air-padded headboxes. - Answers :Which of the following unit
operations of a typical Fourdrinier paper machine with a conventional air-pad headbox
is least likely to reduce the molecular mass of a polymeric additive that becomes
exposed to that operation?
A. Fan pump
B. Hydrocylone cleaners
C. Pressure screen
D. Headbox
Quill - Answers :An additive is being injected into the center of flow, keeping it away
from the walls.
Dilution when adding chemicals - Answers :Dilute the additive stream with enough water
so that its velocity significantly exceeds the average velocity within the stock line. The
"jet" of additive helps to momentarily fluidize the fiber suspension. Another factor that
helps mixing of the chemical additive is the lower viscosity that can result from diluting a
chemical additive.
Addition before a bend - Answers :The bend in a pipe creates momentary turbulent flow
and allows a good amount of mixing between the additive and the pulp. Can also
remove clumps/plugs of fibers.
A - Answers :Which of the following papermaking terms has the broadest definition,
according to Chapter 1?
A. Furnish
B. Stock
C. Pulp
D. Fiber
White water - Answers :Water that is removed from the wet web in the forming section.
This includes water that is removed by gravity, by the action of hydrofoils, by blades or
forming rolls (in some twin wire systems), or vacuum.
There is the presence of fine material, such as fiber fines, mineral fillers, and bubbles of
air.
Scatters light
Non-integrated mill - Answers :Pulp is purchased in the form of dry bales.
These mills utilize a pulper.
Thick stock - Answers :Slurries with consistency of 3-5%.
Refining - Answers :An early technology of this mechanism is the Hollander beater,
which is oval in shape.
Repeated passes through a beating operation tend to make the fibers more flexible and
comfortable. This increases the area of adhesion (RBA) between fibers.
Blend chest - Answers :The location in which papermakers combine different streams of
stock into the system. Refining of each type of fiber is done before this location.
Machine Chest - Answers :Acts as a buffer capacity in the system. Provides a reservoir
of stock so that papermakers can make quick adjustments in the rate at which stock is
pumped towards the paper machine.
Freeness - Answers :A measure of the rate at which water drains from fiber in the
forming process.
Allows papermakers to achieve a better combo of strength properties at a given level of
freeness. - Answers :What is the purpose of separate refining?
Tickle refiners - Answers :By having one or more of these relatively late in the process,
papermakers can make quick adjustments and begin to see the results of such
adjustments a few minutes later.
The refining plates and general design of these are often selected to give a relatively
harsh, cutting action.
Increase in load and decrease in space between refining plates = decrease in freeness
and fiber length.
Stuff box - Answers :Provides a constant head so that the flow of thick-stock furnish to
the paper machine can be accurately controlled with a valve farther downstream.
Excess furnish is recirculated back into the machine chest. Often the last point where a
chemical can be added as a stream coming out of a simple hose at ambient pressure.
Stock valve - Answers :A papermakers primary tool for adjusting the basis weight of
paper. Controls the flow of thick stock to the paper machine.
A constant head
A steady, known value consistency
An accurate measurement of the total flow - Answers :Steady, accurate control of thick
stock flow requires 3 things:
,Mag meter - Answers :Magnetic flow analyzer
Obtains an accurate measure of total flow
After screening. This point is often positioned close enough after the pressure screens
so that it can still take advantage of the turbulent eddies generated by that operation. -
Answers :When is the last chance to add a chemical?
Ring header - Answers :Utilized to add chemical at four different points around the
circumference of the stock line. Often used for retention aid.
Injection quill - Answers :A type of pipe arrangement that discharges the additive near to
the center of flow within the stock line.
Approach Flow - Answers :Conveys the stock to the paper machine headbox, and at the
same time, spread the flow so that it matches the width of the paper machine.
Intake manifold - Answers :Where the flow is spread to the width of the paper machine.
On older paper machines this may consist of a series of dividing pipes.
Now it consists of a tapering header with tubes coming off from it at a right angle.
To knock down foam and prevent accumulation of deposits at the water line. - Answers
:Why are showers placed within air-padded headboxes?
Action - Answers :A moderate level of _______ tends to increase the rate of drainage
and produce a less flocky sheet. If it is too severe, blemishes can occur in the paper,
sometimes leading to web breaks.
Deculator - Answers :A deaeration system.
This unit applies a partial vacuum to the furnish, causing release of dissolved gases.
Minimizes some of the problems caused by dissolved or entrained air. These problems
can include pinholes in the paper, circular marks on the paper surface, and a significant
reduction in drainage rate.
Save-all - Answers :When excess white water leaves the primary circuit, the overflow
stream is directed to this device to avoid wasting all of the fine solids.
save - all . In modern paper mills it is common to find disc filters being used as these.
Sweetener - Answers :It is conventional practice to add a moderate level of pulp fibers
as this to help filter the fine material, and avoid its loss as effluent. Many paper machine
systems employ broke stock for this purpose.
Broke - Answers :Defined as repulped furnish; it tends to vary in unpredictable ways
due to paper breaks, grade changes, coating operations, and the fact that it can be
generated at different points in the papermaking process.
Hydrodynamic shear
, On a typical Fourdrinier, the pressure screens achieve some of the highest shear stress
values. - Answers :A change in velocity of fluid with distance, multiplied by a coefficient
of viscosity.
One had to consider this variable when adding chemicals to a process.
D.
especially in the case of an air-padded headbox
But hydraulic headboxes usually can be expected to impart higher levels of
hydrodynamic shear than air-padded headboxes. - Answers :Which of the following unit
operations of a typical Fourdrinier paper machine with a conventional air-pad headbox
is least likely to reduce the molecular mass of a polymeric additive that becomes
exposed to that operation?
A. Fan pump
B. Hydrocylone cleaners
C. Pressure screen
D. Headbox
Quill - Answers :An additive is being injected into the center of flow, keeping it away
from the walls.
Dilution when adding chemicals - Answers :Dilute the additive stream with enough water
so that its velocity significantly exceeds the average velocity within the stock line. The
"jet" of additive helps to momentarily fluidize the fiber suspension. Another factor that
helps mixing of the chemical additive is the lower viscosity that can result from diluting a
chemical additive.
Addition before a bend - Answers :The bend in a pipe creates momentary turbulent flow
and allows a good amount of mixing between the additive and the pulp. Can also
remove clumps/plugs of fibers.
A - Answers :Which of the following papermaking terms has the broadest definition,
according to Chapter 1?
A. Furnish
B. Stock
C. Pulp
D. Fiber
White water - Answers :Water that is removed from the wet web in the forming section.
This includes water that is removed by gravity, by the action of hydrofoils, by blades or
forming rolls (in some twin wire systems), or vacuum.
There is the presence of fine material, such as fiber fines, mineral fillers, and bubbles of
air.
Scatters light
