An Improved Process and Apparatus for Bleaching Paper Pulp and other similar Vegetable Substances.
Year: 1891

page_text: COMPLETE SPECIFICATION.
An Improved Process and Apparatus for Bleaching Paper Pulp and
other similar Vegetable Substances.
I CARL KELLNER Director of the Kellner-Partington Paper Pulp Company
Limited of New Market Lane Brown Street Manchester in the County of
Lancaster, 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 :—
The object of this invention is to bleach paper pulp and other similar vegetable
substances by chlorine gas in a continuous manner and by a single process.
The nature of my said invention and the manner in which the same is to be
performed or carried into practical effect will be readily understood on reference
to the annexed sheet of drawings and the following explanation thereof.
The invention consists principally in the bleaching of the paper pulp or other
similar vegetable substance by causing the same to be moved continuously in one
direction against a continuous counter current of chlorine gas flowing in the
opposite direction.
The apparatus may be so arranged that the paper pulp or other vegetable
substance to be bleached is caused to be moved either in a continuous spiral or in
an alternative or zig-zag direction and the apparatus may be placed in a vertical,
diagonal or horizontal position, the pulp in the latter case being carried along by a
revolving screw or equivalent.
In the annexed drawing I have illustrated an apparatus which I have specially
designed for the purpose, Fig. 1 being an elevation of the same (drawn partly in
section) Fig. 2 a horizontal section and Fig. 3 an enlarged section of a detached
portion thereof hereinafter more particularly referred to.
A is a tower which is divided into a number of compartments by a series of
horizontal plates or false bottoms a as shown at the lower part of Fig. 1.
b
This tower is preferably made of earthenware and constructed as shewn on the
detached enlarged sectional view Fig. 3. Each horizontal plate or false bottom a
is made in one piece with a ring provided at its upper edge with a circum-
ferential gutter, in which water is placed, and the lower edge of each ring rests
in the gutter of the ring immediately below it so as to form a water-tight joint,
and a sufficient number of these sections are thus built up one above the other to
form a tower A of the required height. The tower is closed at top and bottom
with the exception of the inlet and outlet openings hereinafter mentioned.
Each division plate a is provided at one point with a long radial opening or
slot d and these openings in the different plates are so arranged with regard to
each other (see dotted lines on Fig. 2) that each one is a little in advance of the
other so that paper pulp falling through one slot shall fall upon the solid part of
the next plate just past the slot therein, the slots being arranged in a spiral
direction from top to bottom of the tower A. Through the centre of all the plates a
passes a vertical shaft e (preferably of iron plated or otherwise suitably protected
from the action of the chlorine) and this shaft is provided in each compartment
with a radial arm (preferably of wood).
The shaft e has a slow revolving motion given to it by worm gearing 9 and
as it revolves the radial arms sweep the upper surface of the division
plates a.
is an inlet pipe for the introduction of a continuous supply of chlorine gas
from an electrolytic decomposing apparatus or other source to the lowest compart-
ment of the tower A and i is an exit opening at the top for the emission of the
spent gas from the same.

page_text: kis a hopper into which the wet pulp is fed from a thickener or strainer and this
hopper is provided with a pair of squeezing rollers which are caused to revolve
and are pressed together by springs or otherwise.
The pulp falls from this hopper into the first compartment and is carried round
by the radial arm until it reaches the radial slot or opening d through which it
falls into the next compartment and so on from top to bottom where it is swept out
by the lowest arm through the exit opening m.
Meanwhile the chlorine gas entering in a continuous stream at h in the lowest
compartment rises in an upward countercurrent in a spiral direction through the
openings or slots d from one compartment to another till it reaches the top the
spent gas escaping at the opening the chlorine having by that time been entirely
absorbed by the descending wet pulp.
The height of the tower A and the rate of supply of chlorine gas and wet pulp
respectively must be so proportioned that a sufficient amount of chlorine shall be
admitted to saturate and bleach the whole of the pulp as it passes through and
that the gas shall be practicably spent by the time it reaches the exit opening i.
The hydrochloric acid produced by the chemical reaction of the chlorine on the
hydrogen in the wet pulp is washed out by passing the pulp from the exit
opening m against a current of water moving in the opposite direction and the
hydrochloric acid thus obtained may be utilized by passing it back into the
electrolytic decomposing apparatus employed for the generation of the chlorine
gas used in the process.
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 :-
-
First. The improved process of bleaching paper pulp and other similar
vegetable substances by causing the same to pass continuously through a tower or
chamber in the opposite direction to a countercurrent of chlorine gas substantially
as hereinbefore described.
Secondly. I claim the construction of the apparatus substantially as herein-
before described and illustrated by the drawing annexed whereby the wet pulp or
other vegetable fibre is caused to descend continuously in opposition to a
continuously ascending current of chlorine gas.
Thirdly claim the method hereinbefore described of utilizing the hydro-
chloric acid formed in this process by returning the same into the electrolytic
decomposing apparatus used for the generation of the chlorine gas employed.
Dated this 22nd day of December 1891.
GEO. DAVIES & SON,
4, St. Ann's Square, Manchester, Agents for the Applicant.