The apparatus forming the subject of this invention was designed by
Francis A. Cloudman, Erwin B. Newcomb, and Frank H. Cloudman, of
Cumberland Mills, Me., and comprises a series of tanks or chests, two
or more in number, through which the material to be bleached is caused
to pass, being transferred from one to the next of the series in
order, while the bleaching agent is caused to pass through the series
of chests in the reverse order, and thus acts first and at full
strength upon the materials which have previously passed through all
but the last one of the series of chests and have already been
subjected to the bleaching agent of less strength.
For convenience, the chest in which the material is first introduced
will be called the "first of the series" and the rest numbered in the
order in which the material is passed from one to the other, and it
will be understood that any desired number may be used, two, however,
being sufficient to carry on the process.
The invention is shown embodied in an apparatus properly constructed
for treating pulp used for the manufacture of paper, and for
convenience the material to be bleached will be hereinafter referred
to as the pulp, although it is obvious that similar apparatus might be
used for bleaching other materials, although the apparatus might have
to be modified to adapt it for conveying other materials of different
nature than pulp from one bleaching chest to the other and for
separating out the bleaching liquid and conveying it from one chest to
the other in the reverse order to that in which the material passes
from one chest to the next.
The pulp material with which the apparatus herein illustrated is
intended to be used is retained in suspension in the bleaching liquid
and flows readily through ducts or passages provided for it in the
apparatus in which the pulp to be bleached and the bleaching liquid
are introduced together at the bottom of each chest and flow upward
therethrough, while at the top of each chest there are two conveyors,
one for carrying the pulp from one chest to the next in order, while
the other carries the bleaching liquid from one tank to the next in
the reverse order, the said conveyors also acting to partially
separate the pulp from the liquid in which it has been suspended
during its upward passage through the chest.
Suitable agitators may be employed for thoroughly mixing the materials
in the chest and in the apparatus shown the bleaching agent and
material to be bleached pass through each chest in the same
direction--namely from the bottom to the top--although they are
carried from one chest to the next in the reverse order, the material
to be bleached being primarily introduced into the chest at one end of
the series, while the bleaching agent or solution is introduced
primarily into the chest at the other end of the series.
Fig. 1 is a plan view of an apparatus for bleaching in accordance with
this invention, comprising a series of four chests, and Fig. 2 is a
vertical longitudinal section of a modified arrangement of two chests
in line with one another, and with the conveyor for the material to be
bleached and the passage through which said material passes from the
top of one chest into the bottom of the next chest in the plane of
section.
[Illustration: Fig. 1]
The chests, _a_ _a2_ _a3_ _a4_, may be of any desired shape
and dimensions and any desired number may be used. Each of said chests
is provided with an inlet passage, _b_, opening into the same near its
bottom, and through this passage the materials are introduced. The
unbleached material, which may be paper pulp or material which is
readily held in suspension in a liquid and is capable of flowing or
being conveyed from one point to another in a semi-fluid condition, is
introduced through the inlet passage, _b_, to the first chest, _a_, of
the series, said pulp preferably having had as much as possible of the
liquid in which it was previously suspended removed without, however,
drying it, and, together with the said pulp, the bleaching agent which
has previously passed through the other chests of the series, as will
be hereinafter described, is introduced so that both enter together at
the lower portion of the first chest, _a_, of the series. The said
materials are caused to flow into the chest continuously, so that the
portion at each moment entering tends to displace that which has
already entered, thus causing the materials to rise gradually or flow
upward from the bottom to the top of the chest.
Suitable stirring devices or agitators, _c_, may be employed to keep
the pulp in suspension and to expose it thoroughly and uniformly to
the liquid introduced with it.
[Illustration: Fig. 2]
When the materials (the pulp and the bleaching liquid) arrive at or
near the top of the chest, they are partially separated from one
another and removed from the chest at substantially the same rate that
they are introduced, as follows: Each chest is provided at its upper
part with a liquid conveyor, _d_, having a construction similar to
that of the device known as a "washer" in paper making machinery,
consisting of a rotating drum, the periphery of which is covered with
gauze, which permits the liquid to pass into it, but excludes the pulp
suspended in the liquid, the said drum containing blades or buckets
that raise the liquid which thus enters through the gauze and
discharges it at _d2_ near the axis of said drum. There is one of
these washers in each one of the series of chests, and each discharges
the liquid taken from its corresponding chest into the inlet pipe of
the next preceding chest of the series, the washer in the chest,
_a4_, for example, delivering into the inlet passage, _b_, of the
chest, _a2_, and so on, while the washer of the first chest, _a_,
of the series delivers into a discharge pipe, _e_, through which the
liquid may be permitted to run to waste or conveyed to any suitable
receptacle, if it is desired to subject it to chemical action for the
purpose of renewing its bleaching powers or obtaining the chemical
agents that may be contained within it.
The operation of the washers in removing the liquid from the upper
part of the chest tends to thicken the pulp therein, and the said
thickened pulp is conveyed from one chest to the next in the series by
any suitable conveying device, _f_ (shown in this instance as a worm
working in a trough or case, _f2_), which may be made foraminous
for the purpose of permitting the liquid to drain out of the pulp that
is being carried through by the worm, in order that the pulp may be
introduced into the next chest of the series as free as possible from
the liquid in which it has been suspended while in the chest from
which it is just taken. The pulp is thus conveyed from one chest in
the series to the inlet passage leading to the next chest of the
series, and in the said inlet passage it meets the liquid coming in
the reverse order from the next chest beyond in the series, the pulp
and liquid thus commingling in the inlet pipe and entering the chest
together, and being thoroughly mixed by the agitators in passing
through the chest by the continued action of fresh material entering
and of the conveyors taking the material out from the chests. In the
last of the series of chests into which the pulp is introduced the
fresh or strong bleaching liquid is introduced through a suitable
inlet pipe, _g_, and the pulp conveyor, _f_, that takes the pulp from
the last chest, delivers it into a pipe, _h_, by which it may be
conveyed to any desired point, the said pulp having been sufficiently
bleached before arriving at the said pipe, _h_. It will be seen that
by these means all the pulp is thoroughly and uniformly subjected to
the bleaching agent and that the bleaching is gradually performed in
all parts of the pulp, which is first acted upon by the weaker
bleaching agent that has previously operated upon the pulp before
treated, and that finally, when nearly bleached, the pulp is acted
upon by the bleaching material of full strength, this action being far
more efficient than when the materials are simply mixed together, the
unbleached material with the strong bleaching agent, and allowed to
remain together until the bleaching operation is finished, in which
plan the bleaching agent loses its strength as the bleaching operation
approaches completion, so that when the pulp is nearly bleached it is
operated upon by a very weak bleaching agent. By having the pulp
transferred from one chest to the next in the reverse order to that in
which the liquid is transferred it will be seen that all parts of the
pulp are acted upon uniformly and equally and that the operation may
go on continuously for an indefinite period of time without
necessitating stopping to empty the vats, as is the case when the
liquor only is transferred from one vat to the next. A pump may be
used for lifting the bleaching liquid, as shown, for example, at _k_,
Fig. 1. where said pump is used to raise the liquid delivered from the
chest, _a2_, and discharge it into the trough, _m_, by which the
pulp is carried to the inlet pipe, _b_. By the use of the pump, _h_, a
stronger flow of the liquid into the pipe _b_, of the first chest,
_a_, is effected than if it were taken directly from the washer of the
chest, _a2_, which is desirable, as the pulp is delivered in the
trough, _m_, with but little moisture.
It is obvious that the construction of the apparatus may be varied
considerably without materially changing the essential features of
operation. For example, the washers might be dispensed with and the
liquid permitted to flow through suitable strainers from one chest to
the next in order, by gravity, the successive chests in the order of
the passage of the pulp being placed each at a higher level than the
preceding one, and it is also obvious that the construction of the
pulp conveyors might be widely varied, it being essential only that
means should be provided for removing the pulp from one chest and
delivering it into the next while carrying only a small amount of the
liquid from one chest to the next with the pulp.
* * * * *
THE USE OF COMPRESSED AIR IN CONJUNCTION WITH MEDICINAL SOLUTIONS IN
THE TREATMENT OF NERVOUS AND MENTAL AFFECTIONS.