Improvements in Pulp Strainers of Paper Making Machines.
Year: 1893

page_text: Date of Application, 17th June, 1893.
Complete Specification Left, 11th Dec., 1893-Accepted, 13th Jan., 1894
PROVISIONAL SPECIFICATION.
Improvements in Pulp Strainers of Paper Making Machines.
I, DAVID NOBLE BERTRAM of St. Katherines Works, Sciennes Edinburgh,
in the County of Midlothian, North Britain, Engineer, 'do hereby declare the
nature of this invention to be as follows:-
:-
The invention relates to improvements in pulp strainers of paper making
machines.
This strainer in accordance with my said invention has been constructed to
overcome the objections which are more or less attached to the various classes of
strainers previously in use, for example in accordance with my invention no hanks,
knots, or unboiled fibres remain on the surface of the plates, nor come in contact
with the strainer plates after they have been separated from the clean pulp. The
revolving strainer and others having an oscillating motion cause the pulp around
them and on their surface to be kept in a state of agitation and in contact with the
plate surfaces, and thus the deleterious matter is most liable to be sucked through
and passed on to wire.
In my new strainer the plates are set at an incline and in lieu of allowing the
pulp to flow in at the end of the strainer I cause the pulp to be discharged upon
the apex or top of the inclined plates, along the length of the strainer in lieu of
at the end of the strainer and I reverse the slits in the plates.. The stuff is run
off by a channel at the bottom of the inclined plates. The arrangement may be
double that is to say the plates may be inclined at both sides of the machine. The
pulp is allowed to flow equally over the whole length of the straining surface from
the apex to the bottom of incline, the length of apex being 6 feet and the flow of
pulp therefrom to under end of plates 30 inches, or this distance could be made
greater or less as desired and the angle of plate altered in the various strainers to
suit requirements.
By such a course the clean pulp is passed through the plates before the
objectionable matter can rest thereon, such objectionable matter being carried by
the impetus of the stuff into a channel at lower end of plate. This is effected by
the quantity of pulp passing into the channel, which is usually employed when the
strainers are working in connection with an auxiliary. In this channel I place zinc
plates with longitudinal or cross slots through which the heavy dirt passes into the
under channel and remains there, and on the top the flow is conducted to an
auxiliary strainer which cleans the pulp in the usual manner when auxiliary
strainers are employed, and the heavy pulp is taken out when washing up or it may
be run off with a cock at end. It will thus be seen that the dirt or deleterious
matter when once clear of the. plates does not again come in contact with the
straining surfaces as is the case with the afore mentioned oscillating and revolving
strainers..
In the original flat strainer the plate surface was 6 feet long by 2 feet wide.
The pulp having to flow longways, the dirt or deleterious matter settled on the
second plate or according to the amount of overflow employed, and the first plate
passed the greatest quantity of the pulp passing through the strainer plates.
Thus it will be seen that the entire surface of this strainer acts in the same manner
as the first plate in the original strainer, and in this way increases the efficiency
of the straining area to such a degree that it may be said that there is a straining
area of 15 square feet equal in efficiency to the first plate in original strainer, the
area of which is however only 3 square feet.

page_text: The diaphragm will be made practically the full length of strainer plates, and
arranged so that the pulp as it flows first on to the plates will be submitted to a
stronger suction than at the low end where the deleterious matter passes over the
plates at a slower speed.
To ensure an easy discharge from below strainer plates of the pulp after it has
been passed through the strainer plates I introduce a discharge channel the full
length of inside of vat, thus ensuring an equal suction over all the area of plates,
and also the free exit of the pulp after being passed.
The spreading of the pulp I effect by a hinged lip-board attached to the strainer
spout which conveys the pulp thereto. Along this lip-board place bars which
can be lifted or lowered according to the quantity of pulp required to be passed
on to strainer, the pulp flowing through below these bars so as to get it all
thoroughly spread.
The box into which the pulp: is delivered is fitted with a regulating sluice
actuated by screws and mitre gear.
Dated this 16th day of June 1893.
JOHNSONS,
115, St. Vincent Street, Glasgow, Applicant's Agents.
COMPLETE SPECIFICATION.
Improvements in Pulp Strainers of Paper Making Machines.
I, DAVID NOBLE BERTRAM, of St. Katherines Works, Sciennes Edinburgh,
in the County of Midlothian, North Britain, Engineer, do hereby declare the
nature of this invention and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement :-
This invention relates to improvements in pulp strainers of paper making
machines and has for its object, the construction of a strainer which will overcome
the objections hitherto attached, more or less, to the various classes of strainers at
present in use, that is to say, that in accordance with my said invention no hanks,
knots or unboiled fibres will remain on the surface of the plates, nor come in
contact with the strainer plates, after they have been separated from the clean
pulp.
The revolving strainer, and other strainers having an oscillating motion, hitherto
used, cause the pulp around them, and on their surface, to be kept in a state of
agitation and in contact with the plate surfaces, and thus permit of the liability of
the deleterious matter being sucked through the strainer plates and passed on to the
wire of paper making machines.
In carrying out my invention as hereafter described with reference to the
accompanying drawings, which illustrate, in elevation Figure 1, and cross section
Figure, 2, a strainer constructed in accordance therewith, I proceed as follows:-
I mount the strainer plates A, in such a manner, that they lie in an inclined
plane, and in lieu of allowing the pulp to flow in at the end of the strainer as
hitherto, I cause the pulp to be discharged along and upon the apex or top B of
the plates A, the slits being reversed, that is to say, the slits lie along the length of
the plates so that the pulp in flowing over them, flows at right angles to the length
of slits. The pulp flows equally over the-surface of the strainer plates A from the
apex to the bottom of the incline which is or may be about 6 feet in length or
breadth and about 30 inches in depth and is very efficiently strained from any
objectionable matter and the said objectionable matter is carried away by the
impetus of the stuff into a channel C, before it has time to settle on the surface of
the plates; the said channel C being formed at the lower end of the plates A, and
extending from side to side of the vat. The strained' or clean pulp after passing

page_text: through the plates. A enters a discharge channel D, which is formed, or provided
under the lower end of the plates A as shown; said channel D extending across
the full length of the vat so as to ensure of an equal suction over all the area of
the plates A, as well as to form a free exit or passage for the strained or clean
pulp.
The diaphragm E is practically made the full length of the strainer plates A and
it is preferably so arranged and mounted at an angle to the strainer plates, as shown
in Figure 1, as to cause the pulp, firstly, as it flows on to the plates, to be subjected
to a stronger suction than is the case at the low end of the plates were the
deleterious or objectionable matter passes over the plates at a slower speed, and
secondly, to ensure that no pulp lies beneath the plates for any length of time
before getting out at the outlet, as is the case with diaphragms.set level.
The spreading of the pulp is effected by a sluice fixed in the channel F, as shown
in section Figure 2, and the pulp is run in over the edge of the vat and through
below the sluice which regulates the flow equally all over the length of the apex B
of the plates.
The arrangement is such, that the clean pulp is passed through the plates before
the objectionable or deleterious matter rests thereon, such matter being carried
away by impetus of the stuff into the channel C, which is effected by the quantity
of pulp passing into the channel which is usually employed when the strainers are
working in connection with an auxiliary, and in which I mount zinc plates having
longitudinal or cross slits through which the heavy dirt passes into the under
channel and remains there until it is cleaned out, when washing up, or it may be
run of by a cock. The flow from the upper channel is conducted to the auxiliary
strainer which cleans the pulp in the usual manner as hitherto. It will thus be
seen that the dirt or deleterious matter when once clear of the plates does not again
come in contact with the straining surfaces, as is the case with oscillating and
revolving strainers.
In the ordinary style of flat strainer having a plate surface of about 6 feet long
by 2 feet wide over which the pulp flowed lengthwise, the dirt or deleterious matter
settled on the second, third or fourth plate according to the amount of overflow
employed, and the first plate passed the greatest quantity of the pulp which passed
through the strainer. Now in the strainer constructed according to the present
invention the entire surface of the strainer-acts in the same manner as the first
plate in the flat strainer, and in this way increases the efficiency of the area to such
a degree that it may be said there is a straining area of about 15 square feet, equal
in efficiency per square foot, to the first plate of flat strainer, the area of which is
only about 3 square feet.
The arrangement may be double, that is to say, the plates may be inclined at
both sides of the machine having either one inlet channel for the pulp and two for
running deleterious pulp to the auxiliary or vice versa, and the size of the plates, as
well as the angle in which they are placed may be varied as required so as suit
various strainers.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1st. In pulp strainers of paper making machines, mounting the strar, er plates at
an angle and in such a manner that the stuff is caused to flow down over the same
from the apex or top thereof, substantially as and for the purpose hereinbefore
described and shown in the accompanying drawings.
2nd. In pulp strainers of paper making machines, mounting the diaphragm at
an angle relatively with the strainer plates, substantially as and for the purposes
hereinbefore described and shown in the accompanying drawings.
3rd. In pulp strainers of paper making machines, so mounting the discharge
channel or outlet D, that it extends from side to side of the machine, substantially

page_text: as and for the purposes herein before described and shown in the accompanying
drawings.
Dated this 9th day of December 1893.
JOHNSONS,
115, St. Vincent Street, Glasgow, Applicant's Agents.