A New and Improved Blowing-out and Washing Process in Making Paper Pulp from Esparto, Straw, and other similar Vegetable Substances.
Year: 1888

page_text: Date of Application, 1st Aug., 1888
Complete Specification Left, 31st May, 1889-Accepted, 1st Aug., 1889
PROVISIONAL SPECIFICATION.
A New and Improved Blowing-out and Washing Process in Making
Paper Pulp from Esparto, Straw, and other similar Vegetable
Substances.
I CARL FERDINAND DAHL Engineer 35 Eastcheap, London do hereby declare the
nature of this:invention toibe as follows:
In this process the esparto, straw or other similar substance being previously
cleaned but otherwise either left in their natural state, that is to say without being
cut, or being cut as usual is put into the boiler which is filled with a lye mixture
composed partially of a caustic soda lye and partially of the washing water from a
previous boiling, and is boiled under pressure for from 4 to 10 hours as usual. By
opening a valve the contents of the boiler is carried under a pressure of from 20
to 45 pounds into a closed cylinder provided with safety valves allowing a pressure
of about 8 pounds.
In this cylinder the washing of the boiled matter is done by means of steam, warm
washing lye and water under pressure, and the incrustation lye resulting from the
process (black lye) is evaporated in order to recover the alcali.
into pulp.
=
The difference of pressure in the boiler and the blowing out cylinder
(45 lb. 8 lb. 37 lbs.) causes a complete separation of the fibres of the boiled material
The washing under pressure and at a temperature corresponding to the pressure
prevents the atmospheric air from entering and thus allows of a quick and complete
washing out of the lye.
-
Having extracted or washed out all the lye a valve on the blowing out cylinder is
opened and the clean material is led into a vessel provided with an agitator. From
this vessel the pulp without requiring any further treatment nor disintegration in a
rag engine is taken to the bleaching vat and then treated as usually in the
manufacturing of paper.
Dated this 1st day of Anno 1000
COMPLETE SPECIFICATION.
A New and Improved Blowing-out and Washing Process in Making
Paper Pulp from Esparto, Straw, and other similar Vegetable
Substances.
L, CARL FERDINAND DAHL of 35 Eastcheap, London, E.C. and of Danzig, Germany,
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 :-
My process is particularly described as follows:-The Esparto, Straw and other
vegetable substances, after being cleaned, and cut or not as may be desired, are
brought into a Boiler (a), preferably of vertical cylindrical, conical ended form as shewn,
and there as usual boiled under pressure with a caustic lye for from 4 to 10 hours.
At the completion of the boiling, the Boiler at the same time being under a
pressure of from 20 to 45 lbs., a discharge valve (c), fixed in the lowest part of the
Boiler is opened, and the whole contents of the Boiler are driven out through the said
valve and blow out pipe (d.) into a closed washing vessel (6).
This washing vessel, preferably of cylindrical form, is provided with one or more
safety valves (e.) loaded to a pressure of about 8lbs. per square inch. The difference
between this pressure and the pressure in the Boiler being that available for blowing out.
'מ

page_text: The passage and discharge of the boiled mass, under this pressure difference, cause
a complete disintegration of the fibres into pulp.
The washing of the pulp in a closed vessel under pressure, the pulp at the same
time being consequently out of contact with the air, is effected, first with warm
washing lye, then with warm water and finally with cold water, all entering in turn
through a perforated pipe (p.), placed in the upper part of the cylinder.
At the completion of the washing, a discharge valve (f.) is opened at the bottom
of the cylinder and the contents are driven by the aforesaid pressure into a vessel for
further treatment by bleaching &c. as is usual in the manufacture of Paper.
The liquor first discharged from the washing cylinder is led away to the Soda
recovery apparatus, or if required is used partly to form, with fresh caustic lye, a
preliminary boiling liquor, later on the discharge wasbing liquor is stored to form a
first warm washing lye as herein before described.
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 :-
1. The method of automatically discharging the contents of a Boiler by steam
pressure, as applied to Boilers for Esparto, Straw and other vegetable substances and
by means of a pipe leading the boiled pulp in any direction that may be required
direct to the washing vessel.
2. The method of washing the pulp under pressure, and out of contact with air, in
a closed vessel into which the contents of the Boiler have been discharged, and from
which the said contents when washed can be automatically driven out for further
treatment.
1000
CARL FERDINAND DAHL.