GAS FIRED DIGEster, FOR USE IN THE MANUFACTURE OF PULP FOR PAPER-MAKING FROM WOOD STRAW AND THE LIKE
Year: 1884

page_text: THOMAS ANDERSON REID 19 Bedford Road, Bootle near Liverpool, Practical
Chemist, do hereby declare the nature of my invention for GAS FIRED DIGEster,
FOR USE IN THE MANUFACTURE OF PULP FOR PAPER-MAKING FROM WOOD STRAW
AND THE LIKE to be as follows :-
In manufacturing Pulp from wood & by chemical methods, the digesting process
is generally carried on in vertical wrought iron cylinders, heated either by steam,
from a steam boiler, or by coal or coke fed furnaces, situated at the bottom of the
cylinders, or, digesters.
Experience has shewn that the latter method is more economical than the former.
It has further shewn that there is room for great improvement in the firing of
these digesters used in the treatment of the wood &°.
My invention as hereinafter described allows of the heating being carried on
with gaseous fuel, this being attained by the special form, and arrangement of the
digester, &, necessary flues to same, whereby I am enabled to fire the digester
directly, and with safety, and, economy.
The accompanying drawings shew the special form and arrangement of my
improved digester. The letters in vertical, &, transverse sections refer to the same
parts.
In using my digester for preparing Pulp from wood, say by a solution of caustic
soda, I charge the wood (previously prepared by barking, sawing, chopping, and
crushing) into the digester. At the same time, I run in by pipe E, a solution of
caustic soda, strength, fourteen degrees by Twaddle's Hydrometer. When the
digester is full, I close all valves, put on, and, bolt down manhole cover B. I now
open dampers G, G. The lighted gas passes up flue K¹, and, is drawn through
holes 1, 2, 3, 4, 5, &°. It is diverted by pillar L, round the digester, and, after
passing through holes 1, 2, 3, 4 & on opposite side, passes away by the flue K³.
When the pressure has risen to 120 lbs to 130 lbs per square inch, I keep it at either
pressure for 2 hours. At the end of the 2 hours, I shut off the gas, by closing
dampers G, G. I now open valve on pipe F. and blow the now spent liquor off
for future treatment. On the liquor being blown off, I carefully loosen manhole
cover to allow steam, still in the digester to escape, and when guage N. has fallen to
zero, the cover is hauled off. I now remove cover on discharge pipe C. unscrew
nut I. and remove valve H. by hauling on chain J.
I then wash the digested wood by means of boiling water into perforated wooden,
or, iron waggons. The digested wood can then be taken away and washed, &,
bleached in the usual manner.
Dated this 001 dow of Tuns One thousand night hundund and night frum

page_text: THOMAS ANDERSON REID Ford Bank Cottage, Weston near Runcorn, & formerly
of 19 Bedford Rd Bootle near Liverpool, Practical Chemist do hereby declare the
nature of my invention for " GAS FIRED DIGESTER FOR USE IN THE MANUFACTURE
OF PULP FOR PAPER MAKING FROM WOOD, STRAW & THE LIKE," 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 an improved method of heating digesters or like vessels
used in making paper pulp from wood, straw, &, the like by chemical means, the
said method being attained, preferably, by the use of the apparatus herein described,
&, shewn in accompanying drawings.
In manufacturing paper pulp from wood straw, &, the like by chemical methods,
the digesting process is generally carried on in vertical wrought iron cylinders heated
either by steam from a steam boiler, or, by coal or coke fed furnaces situated below
the bottom of the cylinders or digesters.
Experience has shewn that the latter method is more economical than the former,
it has further shewn that there is room for great improvement in the existing means
employed for the direct firing of the digesters.
My invention as hereinafter described allows of the heating being carried on with
gaseous fuel, the adoption of which to the purpose in question is. productive of safe,
&, economical working.
The accompanying drawings shew the combination of means employed, which
enable me to adapt gaseous fuel to the purpose in question. The similar letters in
vertical, &, transverse sections of drawings refer to similar parts.
"
CONSTRUCTION."
"AA" is an iron cylinder, 20 feet long by 4 feet in diameter, constructed of
wrot iron plates 1 inch thick, all seams being double rivet.ted. "B" is the man
hole for filling the digester or cylinder, this is 18 inches diameter It is covered
by a wrot iron cover secured (when in use) by bolts, &, nuts. "C" is the
discharge pipe for emptying the digester, it is 10 inches in diameter, &, is covered
by a wrot iron cover secured (when requisite) by bolts, &, nuts. "H" is a wrot
iron valve. This valve rests in a seating in the jacket "Y," At the centre of
bottom of "H" is the spindle "H" passing through the collar marked "H" fixed
in neck of discharge pipe. The valve "H" is secured in position by nut "I." The
chain "J" attached to top of "H" is for the purpose of removing the valve
from its seating before emptying the digester.
Y" is a perforated cylindrical iron jacket made up of segments bolted together.
It is placed at a distance of about 2 inches from the inside of the plates of cylinder
or digester, &, extends from the bottom of said cylinder to a position above top of
flues, its object being to ensure a film of liquid always being in contact (during
the time the digester is being fired) with the plates of digester, in that region
exposed to the direct action of the flame.

page_text: In using the apparatus herein described for preparing paper pulp (say from
wood) by a solution of caustic Soda (Sodium Hydrate) I proceed as follows:--
Having first ascertained that valve "H" is in position, &, cover on discharge
pipe "E," I charge the wood (previously prepared by "barking" "sawing,"
"chopping," &, "crushing") into the digester, At the same time I run in by
pipe "D" a solution of caustic soda of a strength of 14 degrees by Twaddle's
hydrometer Each ton of moderately dry wood requires about 520 gallons of soda
solution of the above strength, in any case the wood should be nearly covered
with soda solution. When the digester is full, all valves are closed with the
exception of "O" which is left open for the time being. The cover is now bolted
on manhole "B." Dampers "G", &, "G" are now opened, &, the lighted gas
admitted. The air slides "R" are also so regulated that the gas burns without
much smoke.
The gas passes up flue "K", &, is drawn through the holes 1, 2, 3, 4 &c. It is
diverted by pillar "L" around the digester, (the direction of gaseous current being
shewn in drawings by the arrows) It makes its exit by flue "K". When steain
issues freely from the digester the safety valve "O" is closed, &, loaded to 130 lbs.
When the pressure has risen to 130 lbs per square inch, it is kept at that point for 2
hours longer. It will be found that when pressure is up that the gas may be eased, this
is done by partly closing damper "G", if flues are very hot both dampers may be
completely closed, &, the pressure sustained by the heat of flues, but of course this
is a point upon which the workman must use his own judgment & guided of course
by the indications of the pressure guage. The heating should be so controlled that
the pressure does not rise above 130 lbs by guage, thus avoiding undue blowing
off from valve "O." If by any means there should be an undue amount of pressure,
damper "G" should be closed, &, "G" fully opened, so as to draw heat from the
flues, &, thus cool apparatus.
2
At the end of the 2 hours mentioned above the gas supply (if on) is shut off by
closing damner “G”1 Damper "A" is loft onen Volvos "1 & «TS

page_text: now opened, &, the now spent liquor blown off for future treatment. When 'the
liquor is off, which usually happens, when the pressure has fallen to 80 lbs per square
inch, the manhole cover is to be slackened carefully, to allow steam still in digester to
escape, &, when guage "N" indicates that pressure is nil the cover may be removed.
The cover on discharge pipe "C" is now removed, nut "I" unscrewed, &, valve H
removed by hauling on chain "J." I then wash the digested wood by means of
hot water into perforated wooden waggons placed underneath discharge pipe. The
digested wood can then be taken away, &, washed, &, bleached in the usual
manner.
Having now particularly described and ascertained the nature of my said
Invention, and in what manner the same is to be performed, I declare that what
I claim is
1. The application of gaseous fuel for heating digesters or like vessels used in the
operation of digesting wood, straw, &, the like for the manufacture of paper pulp.
2. The combination of means employed enabling me to adapt gaseous fuel for
heating digesting apparatus for the purposes above described, consisting in the
apparatus herein described of (a) Special form, &, arrangement of flues. (b) The
means adopted for preventing contact of flame with valves or other parts of digester
liable to be injured by such contact, the said combination of means effecting an
improved, &, advantageous result.
This of Mouch 100K