IMPROVEMENTS IN APPARATUS FOR AND IN THE PROCESS OF MANUFACTURING CELLULOSE AND SECONDARY PRODUCTS.
Year: 1883

page_text: LETTERS PATENT to Edwin Ambrose Brydges, of the firm of Brydges & Co
Engineers and Patent Solicitors of 6 St Leonards Terrace Upton in the
County of Middlesex for an Invention of IMPROVEMENTS IN APPARATUS
FOR AND IN THE PROCESS OF MANUFACTURING CELLULOSE AND SECONDARY
PRODUCTS.' communicated to him by A. Mitscherlich of the town of
Hannoversch Münden in the German Empire.
COMPLETE SPECIFICATION filed by the said Edwin Ambrose Brydges at
the Office of the Commissioners of Patents on the 12th September 1883.
EDWIN AMBROSE BRYDGES of the firm of Brydges & C° Engineers and Patent
Solicitors of 6 St Leonards Terrace Upton in the County of Middlesex IMPROVE-
MENTS IN APPARATUS FOR AND IN THE PROCESS OF MANUFACTURING CELLULOSE
AND SECONDARY PRODUCTS communicated to me from abroad by A. Mitscherlich
of the town of Hannoversch Münden in the German Empire
My Invention for manufacturing cellulose and secondary products consists:-
(A) of a system of apparatus of special construction, (B) a special process or method
of manufacture (C) a special composition of the solution employed.
(A.) Apparatus:-
The principal part of the said apparatus is the boiler or cooking vessel consisting of
an iron cylinder which is provided with a novel protective arrangement or device
against the attacks of the solution on the iron of the said apparatus
The protector employed by me possesses the great advantage over all other
similar means that the same can be employed even with unusually large apparatus
with comparatively small expense and well proved durability. The same can also.
be readily repaired without causing any considerable stoppage in the working. By
means of this said cooking apparatus I am enabled to carry out a large, rational
and consequently lucrative business, the apparatus employed being very large, for
instance 4 meters wide and 12 meters long.
The protective covering for the iron cooking cylinder or boiler consists of thin
sheet lead or lead foil which is attached to the interior surface of the cylinder by

page_text: means of suitable adhesive material. In order to attain a thoroughly air and acid
tight connection between the foil and the walls of the boiler I employ a mixture of
tar and pitch which is adhesive at a comparatively low temperature.
This said adhesive mixture is applied in warm condition and the lead foil
attached to the same by means of friction.
If the sheet iron should in any part be damaged the adhesive matter forms in
combination with the lead, a so air tight closure around the said damaged part that
if a leak should appear in the sheet iron the fluid in the boiler will penetrate
through the thin lead foil when a high pressure is employed in the boiler in such
mauner that the fluid which attacks the iron cannot come in contact with or
destroy a larger surface of the said boiler.
After the leaky part of the sheet iron has been stopped from the exterior the
boiler attains its full former efficiency. Thicker, for instance, soldered sheet lead
cannot be attached so well as the adhesive, matter, would not possess sufficient
adhesive power to hold the sheet lead to the upper arched part of the boiler and in
consequence of the more difficult manipulation would not be likely to penetrate all
the cavities or recesses in the sheet iron.
Rear spaces are thus formed by means of which larger surfaces of the boiler can
be attacked and the same rendered ineffective which can scarcely be prevented
when sheet lead is employed with adhesive matter.
Besides this the fluid containing iron can under certain circumstances penetrate
to and mix with the other fluid and act deterioratingly on the process. In order
to avoid the disadvantages inherent to other methods of lining vessels the sheet
lead has been soldered to the entire surface of the sheet iron but this method is
very expensive and has up to now not proved efficient.
In order to protect the lead foil employed by me against mechanical as well as
chemical action I employ a lining of porcelain-like burnt bricks which are little
affected by the crystallisation of the solution penetrating the same.
This protective method possesses the advantage over all others that the same can
be readily made and the operation is certain and safe so that this said process must
be denoted as a great advance in this special line
Systems of leaden tubes serve to heat the contents of the boiler and are arranged
above the bottom of the lower part of the boiler and reach to about half the height
of the same.
Several parallel systems of tubes are employed so that in case steam
should pass from a damaged tube into the boiler, the phases of the developement
during the cooking process would not be deranged or a local superheating created,
in consequence of which the product would be treated unequally and be consequently
almost useless
Should one system of such tubes or pipes become leaky the same is cut off and
the operation continued by employing the other systems.
The material of which these tubes are made consists of lead with a considerable
admixture of antimony which said mass offers greater resistances against the
mechanical and thermic action than pure lead.
The tubes are at one end in communication with the boiler and are closed at the
other by means of water condensation receptacles out of which the water of
condensation is forced under strong pressure.
This arrangement enables me to readily attain a temperature considerably over
100° Centigrade in contradistinction to the ordinary heating tubes with circulation
throughout.
These heating tubes are led into the boiler by means of suitable unions. The
special construction of this arrangement is shown in Fig. 1 of the accompanying
drawings.
An opening e in the wall of the boiler is clad in and outside with sheet lead and
the bronze union or connecting pipe a which is lined with lead passed through the
same, which said union or connecting pipe or tube is provided with screw threads
and is pressed steam tight against the outer wall of the boiler by means of a nut 6
and flange g and also against a larger lead pipe or tube h..

page_text: A suitable nut is screwed over the union or connecting tube a by means of
which the leaden pipe or tube d, which is arranged in the interior of the boiler is
pressed steam tight into the conical part of the threaded connecting piece a for
which purpose a ring of lead or layer of asbestos i is employed.
The boiler is further provided with a suitable connection which is arranged in
like manner as above described. The same carries the important fittings and offers
the great advantage that three such said fittings can be employed, and only one
opening made in the wall of the boiler.
Such openings are as far as possible to be avoided in order to prevent leakage
occuring.
The three fittings mentioned consists of a thermometer, manometer and sample
glass or sampler
An important part of this device is the pipe or tube a to which the thermometer b
which is provided with a protective sheathing is arranged concentrically within a
suitable muff C on which a valve d is fixed outside the boiler in order to permit of
samples of the fluid being taken.
The manometer is also arranged in this said muff in which latter a pipe can also
be arranged for ascertaining the height of the fluid in the boiler-The openings for
feeding the boiler with material and letting off the products of the process are
shown in Fig: 2 of the accompanying drawings and are provided with the lining of
lead foil as mentioned above and also with a cylindrical mantle of thick lead which
is bent up inside the boiler and is pressed with the adhesive material tight on to
the boiler-A similar mantle C is arranged to protect this thick lead lining which
said protective devices are necessary as the lead foil cannot be protected by brick-
work at these points. As soon as the mantle o shows damaged parts the same is
renewed. These auxilliary mantles act as excellent means for preventing the rapid
wearing away of the iron parts of the boiler.
The above described protective device and especially the brickwork cannot as a
matter of course be employed in connection with rotary boilers, and unsurmountable
difficulties stand in the way of employing the efficacious leaden pipes mentioned
above; it will also be difficult to attach the device for the thermometer, manometer
and sampler
After the substances have been subjected to the cooking process described later
on, the prepared material is introduced into suitable apparatus for dividing up or
separating the fibre of the cellulose and for washing the transformed incrusting
substances.
This separating and washing apparatus is similar to a stamping mill and is
shown in Fig: 3-The same consists of a large number of falling stamps a b c d
and a long trough e beneath the same.
This apparatus must however fulfil other functions than is required of a stamping
machine as the mass is not crushed or pulped but merely so pressed that those
parts which easily divide up are separated from the insufficiently cooked hard pieces
(knots, branches &) so that the latter are not crushed and the fibres not mixed
with the broken parts or splitters of such said hard parts.
It is absolutely necessary that the apparatus fulfil this condition as the cooked
mass contains unreduced parts of branches, knots etc which, when entirely crushed
pass into the cellulose which is thus deteriorated in value.
I attain this object in a constructive manner by not allowing the falling stamp d
to strike the bottom of the stamping trough or come in contact with the sides ƒ of
the trough so that the stamp presses the material without crushing the same.
In order to combine a most effective washing arrangement I have constructed the
apparatus on the principles of opposing streams and attain my object as
follows:-
The stamping trough is arranged somewhat on an incline and the cooked or
boiled matter introduced at the lowest end of the said trough whilst the water
flows down the inclined surface.
The stamps are now moved or manipulated in such manner that when each

page_text: stamp strikes, the next lower stamp remains inactive whereas the higher lying
stamp is raised so that the mass is moved by the blow in question upwards which
said process repeats itself in the entire length of the trough. The very large
number of easy pressings to which each particle of the stuff is subjected effects a
good separation of the material without injuring the fibres in the least degree, and
an easy good washing when sufficient water is employed as the fluid is pressed out
of the stuff at each stroke and the material rapidly sucks up water after the
said stroke.
Well known arrangements are further employed to refine the mass and convert
the same into marketable form
B-Cooking process.
If wood is employed for manufacturing the cellulose, the barked wood cut into
pieces of suitable size is steamed in the boiler in a quantity corresponding to the
concentration and quantity of the solution (i.e. the boiler charge) employed. This
steaming process requires, when wood is employed, special attention as the success
of the process depends substantially on the same-The steaming is not supposed to
chemically prepare the wood for the action of the chemicals but is used solely for
the physical purpose of driving the atmospheric air as far as is possible out of the
wood in order to facilitate the penetration of the solution into the interior of the
pieces of wood so that an easy chemical action is attained through the entire wood
and on the other hand a larger quantity of the fluid can be introduced into the
boiler in consequence of the wood so readily taking up the said solution.
、
In consequence of this fact it is possible to employ the space in the boiler to the
greatest possible advantage for instance the fibrous matter in a cubic meter of wood
occupies a space only equal to 28% of the total space occupied by the piece or
pieces of wood so that 72% of the said space remains for the chemically acting
Huid by which means the capacity of the boiler and the entire factory is considerably
increased.
The steaming is carried on for a length of time corresponding to the quality of
the wood. If the same is fresh hewn or float wood the air is removed in a
comparatively short time but on the other hand if the wood is well dried a longer
steaming is necessary so that, through the diffusion of the steam the air is entirely
removed
The expulsion of the air is facilitated by the inflow of cold fluid through which
the steam is condensed and the pressure in the boiler greatly reduced.
Through steaming the wood at higher temperature than 100° Centigrade and
perhaps thereby that the steam cannot pass entirely free through the boiler the
cooking process will be entirely spoiled.
Attention must always be paid that the temperature in steaming does not rise
considerably above 100° Centigrade which is a very important feature of the
manufacture, as has been proven by many and very expensive experiments.
As shown by the foregoing my preparatory steaming process is entirly different
from the steaming of the wood which is employed for ground wood pulp and which
causes a chemical alteration of the wood mass by brewing the same.
After the steaming of the wood is finished the boiler is charged with the solution
of sulphurous acid SO. The quantity of the organic substances to be employed is
governed by the degree of concentration of the sulphurous acid solution which is
variable and depends on the manner of its preparation.
If the proportions between the organic stuffs and the acting substance are not
correct, sulphurous acid compounds may, when too little stuff is present remain in
the fibre and are hard to wash out for instance, when employing bi-sulphite of
lime, sulphite of lime which is hard to dissolve, remains behind.
When this is the case and the fibres are at once worked up into paper, knots
are created in the paper when not handled with great care.
In bleaching the fibres with chloride of lime such salts partially neutralize the
action of the chloride of lime, require considerable additions of the latter, and
render the bleaching process more expensive.

page_text: If, on the other hand, too much organic matter is employed in comparison to the
above named solution the product remains hard and not properly opened up. The
correct proportion varies and must be fixed by the mode of testing given below,
for instance, for pine the proportions are per meter wood, 2 centimeter solution of
1,05 specific gravity or 10 centimeter solution of 1,01 specific gravity.
The
From these figures the other proportions can be readily calculated.
temperature and duration of the process are of special importance. The chief
object of the first phase of the reaction is the slow commencement of the chemical
action which is best carried out at a temperature not much above 108° Centigrade
The following more rapid reaction is carried on at slowly increasing temperature
up to not much above 118° Centigrade.
The conclusion of the reactional process must be fixed with special care and goes
hand in hand with the driving off of the sulphurous acid.
The chemical process is retarded by removing the sulphurous acid and by
lowering the temperature.
In order to be able to observe the progress at this stage and especially the end
of the process I employ a special mode of testing, consisting in taking samples of
the fluid, but, which must be carefully observed, not of the treated wood: this I
effect by means of the fluid sampler as mentioned above.
The manner of controlling the progressing process is that the sample of fluid is
mixed with a body which will indicate the quantity of useful substance in the said
fluid.
If for instance, bi-sulphite of lime is employed the fluid is mixed with ammoniac
and the quantity of matter precipitated observed.
By means of ammoniac and other similar chemical bodies a portion of the
sulphurous acid is absorbed and the sulphite of lime (the important substance for
the cooking process) dissolved by the sulphurous acid precipitated, whilst the salt
formed during the process is not precipitated. One can therefore readily observe
how much useful matter the liquid contains. If for instance the lime compound
is employed and the fluid, when mixed in a divided tube with ammoniac developes
so much precipitate that the same on subsiding amounts to only 1/4 of the volume
of the sample of fluid, the expulsion of the sulphurous acid solution is commenced
and thus a lowering of the temperature produced, practically, to about 106°
Centigrade, and a ready lowering of the steam pressure as steam can freely escape
with the sulphurous acid.
16
If the precipitate amounts to the process is ended and the fluid is then let off
as rapidly as possible. A still smaller amount of precipitate would show that
the process is too far advanced and too little useful substance in the fluid whereby
a free acid most probably sulphuric acid H SO, which, at this high temperature,
even when considerably diluted turns the organic matter brown, is generated
The boiler as described above with its large dimensions and its auxiliary parts
is specially adapted for carrying out this difficult process with certainty and for
which purpose the temperatures given for the different stages are an important
condition
It is true that the cooking process can be accelerated by employing higher
temperatures but the same require on the one hand higher pressure, and on the
other hand give, as my experience shows, a produce in cellulose which is less,
both in quantity and quality and especially as regards the firmness of the same.
The chemical process which takes place during this proceedure consists principally
therein, that in employing wood, the sulphurous acid converts the incrusting
substances in the cellulose into a higher oxydised product at the expense of a part
of the oxygen, and partly into acids which under normal conditions combine with
the base, which is combined with the sulphurous acid, but which, when the
process is incorrectly carried out or the solution is not in proper condition, remain
free and cause a detrimental reaction on the fibres. There arises out of the
incrusting substances besides this acid, chiefly tannic acid of complicated composition
and compounds of the same as auxiliary products,

page_text: C-Condition of the fluid employed.
It is one of the chief requirements for a successful execution of the cooking
process that the sulphurous acid be free from polythionic acid salts-If this is not
the case a decomposition of the substances formed during the process ensues and an
acid is given. free which causes the wood to turn brown or black (most probably
sulphuric acid-Sulphuric acid and oft insoluble sulphuric salts are formed which
deposit themselves in a thick layer on the wood. The wood is not separated by
these polythionic salts, but remains hard and renders the operation effectless.-At
the same time the temperature is raised by this proceedure by several degrees and
the sample taken from the cooking apparatus shows an abnormally rapid reduction
of the sulphurous acid compound. These polythionic acids arise generally through
the appearance of sulphuric vapor in the roasting gases-In order to prevent this
disadvantage I have made it my object to discover the cause of the generation of
such said detrimental compounds and to prevent their occuring by employing a
suitable apparatus.
I attain this so extremely important effect in manufacturing sulphurous acid
compounds which is usually carried out in absorption towers of large size in which
the sulphurous acid is produced by burning pyrites and sulphur, by employing a
testing apparatus or automatic indicator. The same consists of a glass tube similar
to the water guages used with steam engines which is attached to the cooling tube
not far from the furnaces for producing the said sulphurous acid. The hot gases
are cooled in this apparatus and consequently a constant stream created in the
same, so that some of the newly produced gases constantly pass through the said.
glass tube. If sulphuric vapors are present the same will be condensed on the
glass tube in consequence of the low temperature of the same and can be at
once detected by the workman who can immediately do the needful to prevent
this danger.
The foregoing specification of my process will conclusively demonstrate that an
eminently important feature lies in the combined action of a larger number of
details. The same form the basis of my process which, as has been proved by the
successful manufacture, includes the oft attempted solving of a problem, that is,
the production of a white, extremely firm cellulose as substitute for the best rags,
the solving of which said problem I have sought, for the last ten years.
Having now described my said invention and the manner in which the same is
to or may be carried into effect I wish it to be understood that what I claim and
desire to secure by Letters Patent is :-
1. In cooking apparatus for employment with substances which attack metal
and especially for opening up organic bodies, the following improvements
substantially as described in the foregoing specification.
a) The protective lining against the attacks of the agents mentioned above,
consisting of layers of tar and thin sheet lead or lead foil and a lining of brickwork
built of porcelain-like burnt bricks substantially as described in the foregoing
specification
b) The arrangement or device for introducing and fixing several systems of
heating tubes of lead strongly mixed with antimony and also for fixing the
observing and regulating apparatus consisting of the tube a provided with screw
threads and the flange g, the nut b through the screwing up of which the flange g
is pressed snugly against the wall of the boiler and a tight closure made, and the
nut c, substantially as described in the foregoing specification and shown in the
accompanying drawings
2-A separating and washing device or apparatus consisting of a stamp work
with rising, inclined stamping trough and of falling stamps which do not come in
contact with the bottom or sides of the trough and which automatically push the
material forwards, substantially as described in the foregoing specification and
shown in the accompanying drawings.
3-Steaming the wood at about 100° Centigrade for driving the air out of the

page_text: same without turning the material treated brown substantially as described in the
foregoing specification.
4-Method of manufacturing cellulose with subsiduary or secondary products by
means of sulphurous acid compounds (lime, magnesia, alkali) in such manner that
the cooking temperature does not rise considerably above 120° and is so subdivided
that the process is commenced at the low temperature of about 108° Centigrade
then raised to about 118° Centigrade, then lowered and the sulphurous acid almost
entirely driven off and so the process completed. A period of at least 28 hours
should be employed for permitting the chemical action substantially as described
in the foregoing specification, and shown in the accompanying drawings
5-The employment of a method of testing or observing the progress of the
process by examining the fluid samples taken from the boiler in respect to the
quantity of sulphurous acid compound present and thus rendering the employment
of a maximum quantity of wood with a solution of fixed concentration possible,
substantially as described in the foregoing specification and shown in the
accompanying drawings
6. The employment of sulphurous acid solutions which are so manufactured
that they are free from polythionic acid salts substantially as described in the
foregoing specification--and shown in the accompanying drawings
7-The apparatus or device for discovering the presence of sulphuric vapor in
hot gases thus avoiding the formation of polythionic acid combinations in
manufacturing sulphurous acid compounds substantially as described in the
foregoing specification and shown in the accompanying drawings.
.
In witness whereof I the said Edwin Ambrose Brydges have hereunto set my
hand and seal this fourth day of September in the year of Our Lord One thousand
eight hundred and eighty three.
Witnesses,
E. STUTZER.
ANTHONY STEFFEN
EDWIN A DRIDGES
L.S.)