IMPROVEMENTS IN AND IN APPARATUS FOR BOILING AND DIGESTING PAPER STOCK, APPLIC- ABLE ALSO FOR COOKING FOOD FOR CATTLE
Year: 1881

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, for an Invention of "IMPROVEMENTS
IN AND IN APPARATUS FOR BOILING AND DIGESTING PAPER STOCK, APPLIC-
ABLE ALSO FOR COOKING FOOD FOR CATTLE." A communication from
abroad by Henry Coker, of West Point, in the County of Cuming, State of
Nebraska, United States of America.
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark
at the Office of the Commissioners of Patents on the 24th March 1881.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of
Middlesex, Patent Agent. "IMPROVEMENTS IN AND IN APPARATUS FOR BOILING
AND DIGESTING PAPER STOCK, APPLICABLE ALSO FOR COOKING FOOD FOR CATTLE."
[A communication from abroad by Henry Coker, of West Point, in the County
of Cuming, State of Nebraska, United States of America.]
This Invention relates to boilers or digesters for paper stock which heretofore
have been either open or closed vessels, into which the material has been placed
with the lye, and the mass heated by direct application of steam. With such
apparatus and process the steam being injected directly into the digester is con-
densed, and the lye is thus weakened by the addition of the condensed water to
such an extent that chemicals of much greater strength have to be used to allow
for such dilution, and there is besides a waste of heat, and the chemicals are so
much diluted that their recovery is not profitable. The object of this Invention is
to avoid these difficulties and to perform the work more rapidly, effectively, and
economically.
The nature of the Invention consists in heating the mass in the digestor by a
steam heater, and obtaining a circulation of the lye by the variations in specific
gravity.
The apparatus consists of a closed vessel fitted centrally with a closed steam
heater, containing tubes for the circulation of the chemical or caustic lye through

page_text: "
it. The digester or boiler is made of cylindrical form with spherical ends. The
shell is made of boiler iron with cast iron heads that are tied by a rod extending
through the boiler and heater, which rod, to allow of expansion and contraction
without injury to the boiler, is fitted near the upper head with an expansion
socket and keys. The digestor is used in a vertical position. At the upper portion
near the top is a furnishing valve or gate hinged at the upper end to swing inward,
and fitted with clamping bars, by which the valve can be closed tightly, and near
the bottom of the digestor is the discharge valve. The digestor is fitted near the
top with a pressure safety valve, a vacuum safety valve opening inward to allow
inlet of air and prevent collapse by sudden condensation, a large glass water gauge
to show the action of the water in the digestor, a pressure gauge for indicating the
pressure, and a cock to allow escape of air when steam is thrown directly into it;
there is also a pressure gauge and air cock. for the same purpose in the heater.
Near the lower end of the digestor is fitted a perforated false bottom supported by
cross bars or joists that rest on the semicircular end of the digestor. To give
access below the perforated bottom two trap doors will be arranged in the bottom.
From this false bottom rises the heater, the same being placed central of the
digestor, extending a short distance below the false bottom, on which the shell is
"supported by an angle iron, and rising to near the upper end of the digestor. The
heater consists of a hollow cylinder closed at the ends and fitted with numerous
tubes that extend through and are secured to the closed head. The steam space in
the heater outside of the tubes is to be connected with a steam generator by means
- of a pipe that passes through the side of the digestor to the heater, and to provide
against expansion and contraction a double disc expansion joint is used on this
pipe; from the lower end of the heater a pipe passes through the bottom of the
digestor for returning the water of condensation to the generator.
In addition to the steam connections through the pipe described, the boiler is
fitted near the upper and lower ends with pipes which connect with the steam
generator, and are fitted with suitable stop valves for operation by hand to admit
or cut off steam. A pipe with stop valve is also provided at the bottom of the
boiler or digestor for carrying off the dirty water and the spent or partially spent
lye when desired.
The operation is as follows:-The boiler having been furnished through the
upper opening with paper stock, such as straw, wood, rags, waste paper, &c., and
the necessary quantity of caustic lye or other chemical solution added, the gate is
closed, and the liquid portion of the mass in the boiler passing through the
perforated bottom will rise in tubes of the heater and stand at the same level in
both tubes and digestor. Steam is then admitted to the heater at a pressure of
60 lbs. (more or less, according to the nature of the stock), and the tubes of the
heater becoming heated, the lye in the tubes has its temperature raised by indirect
action of the steam, and becoming specifically lighter rises and is discharged
through the upper ends of the tubes upon the mass in the digestor, and a circu-
lation is thus established which becomes violent when the heat reaches the boiling
point. This circulation ensures the contact of the heated lye with every portion
of fibre, so that its work is done rapidly and effectually; at the same time the lye
is not diluted by condensation of steam. The steam first admitted to the heater
rapidly condenses, and the water returns to the generator, but the rapidity of
condensation decreases as the mass in the digestor becomes heated until only
boiling water is returned to the generator, thus effecting a great saving of heat,
which would be entirely lost by the direct process. The condensed steam is not
only hot but pure distilled water, thus avoiding incrustation of the generator, and
at the same time contributing to economy of fuel.
The steam pressure recording indicators show the pressure which is to be
regulated as required until the stock is cooked or it is necessary to change the lye,
when the blow off pipe at the bottom and steam pipe at the top are to be opened.
The steam admitted upon the material will force the lye out either to waste or to
a... suitable. vessel for recovery of. the chemicals. The lye being undiluted its

page_text: treatment for the recovery of the chemicals will be comparatively inexpensive and
profitable.
The cooked stock is removed by the opening at the lower end of the digestor,
but before removal, and if desired during the cooking process, the valve of the
pipe at bottom of the boiler may be opened to admit steam below the stock for
lifting and agitating the mass. This may be continued for a suitable length of
time, and to obtain more effective action a disc valve faced with rubber is provided
to close the pipes in the heater to be operated from the outside by a tube valve
screw, and thereby cause the steam to force the lye through the mass instead of
through the pipes.
The apparatus described is adapted for treating all materials used for paper, the
process being varied as required. The apparatus may also be used for cooking
food for cattle.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Alexander Melville Clark in the Great Seal Patent Office on the
24th September 1881.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of
Middlesex, Patent Agent. "IMPROVEMENTS IN AND IN APPARATUS FOR BOILING
AND DIGESTING PAPER STOCK, APPLICABLE ALSO FOR COOKING FOOD FOR CATTLE."
A communication from abroad by Henry Coker, of West Point, in the County
of Cuming, State of Nebraska, United States of America.
This Invention relates to boilers or digesters for paper stock which heretofore
have been either open or closed vessels, into which the material has been placed
with the lye, and the mass heated by direct application of steam. With such
apparatus and process the steam being injected directly into the digestor is
condensed, and the lye is thus weakened by the addition of the condensed water to
Buch an extent that chemicals of much greater strength have to be used to allow
for such dilution, and there is besides a waste of heat, and the chemicals are so
much diluted that their recovery is not profitable. The object of this Invention is
to avoid these difficulties and to perform the work more rapidly, effectively, and
economically. The nature of the Invention consists in heating the mass in the
digestor by a steam heater, and obtaining a circulation of the lye by the variations
in specific gravity.
The Invention consists in a closed vessel fitted centrally with a closed steam
heater containing tubes for the circulation of the chemical or caustic lye through
it, the heater being in connection with a steam generator, and suitable valves and
gauges provided for regulating the operation and showing the pressure, all as
hereafter described and claimed.
In the accompanying Drawings Figure 1 is a vertical transverse section through
line C, D, Figure 3, of a digestor for paper stock fitted with the improvements;
Figure 2 is a horizontal transverse section of the same through line A, B, Figure 1;
Figure 3 is a top view, Figure 4 is a bottom end view, and Figure 5 is a side
view of disc, valve, screw, &c. Similar letters of reference indicate corresponding
parts.
The digestor or boiler A is made in cylindrical form with spherical ends, and in
suitable size, of any proper proportion of length and diameter. The shell is made
of boiler iron with cast iron heads b, b', that are tied by a rod G extending through
the boiler and heater. To allow of expansion and contraction without injury to
the boiler the rod G is fitted near the upper head b with an expansion socket and
keys W. The digestor A is used in a vertical position. At the upper portion near
the top is a furnishing valve or gate D hinged at the upper end to swing inward,
and fitted with clamping bars e, e¹, by which the valve can be closed tightly.
Near the bottom of digestor A is a discharge valve C. The digestor is fitted near
the top with a pressure safety valve R. (Figure 3), also a vacuum safety valve S
opening inward to allow inlet of air and prevent collapse by sudden condensation.
T is a large glass water gauge to show the action of the water in A. A pressure
gauge will also be fitted on pipe U for indicating the pressure in the digestor, and
a cock to allow escape of air when steam is thrown directly into it. A recording
pressure gauge and air cock for the same purpose will also be fitted on pipe V for
heater B. Near the lower end of the digestor is fitted a perforated false bottom E
(as shown in Figures 1 and 2), which is supported by cross bars or joists F, F,
that rest on the semicircular end of the digestor. To give access below the
perforated bottom E two trap doors x, x, will be arranged in the bottom. From
the false bottom E rises the heater B, the same being placed central of digestor A

page_text: extending a short distance below the false bottom E, on which the shell is
supported by an angle iron c, and rising to near the upper end of the digestor."
The heater consists of a hollow cylinder closed at the ends and fitted with numerous
tubes a that extend through and are secured to the closed head. The steam space
in the heater outside of tubes a is to be connected with a steam. generator by
means of a pipe H that passes through the side of digestor A to the heater B. To
provide against expansion and contraction a double disc expansion joint I is used
on pipe H. From the lower end of the heater a pipe N passes through the bottom
of the digestor for returning the water of condensation to the generator.
In addition to the steam connections through the pipe H described, the boiler A
is fitted near its upper end with a pipe J, and at the bottom with a pipe K, all of
which pipes connect with the steam generator, and are fitted with suitable stop
valves 1, 11, 2, for operation by hand to admit or cut off steam. M is a pipe with
stop valve M¹ at the bottom of the boiler or digestor A. for carrying off the dirty
water and the spent or partially spent.lye when desired.
The operation is as follows:-The boiler having been furnished through the
upper opening with paper stock, such as straw, wood, rags, waste paper, &c., and
the necessary quantity of caustic lye or other chemical solution added, the gate D
is closed, and the liquid portion of the mass in the boiler passing through the
perforated bottom E will rise in tubes a and stand at the same level in both tubes
and digestor. Steam is then admitted to the heater by pipe H at a pressure of
60 lbs. (more or less, according to the nature of the stock), and the tubes a becoming
heated, the lye in the tubes has its temperature raised by indirect action of the
steam, and becoming specifically lighter rises and is discharged through the upper
ends of the tubes upon the mass in the digestor, and a circulation is thus established
which becomes violent when the heat reaches the boiling point. This circulation
ensures the contact of the heated lye with every portion of the fibre, so that its
work is done rapidly and effectually; at the same time the lye is not diluted by
condensation of steam. The steam first admitted to the heater rapidly condenses
and the water returns to the generator, but the rapidity of condensation decreases
as the mass in the digestor becomes heated until only boiling water is returned to
the generator, thus effecting a great saving of heat, which would be entirely lost
by the direct process. The condensed stoam is not only hot but pure distilled
water, thus avoiding incrustation of the generator and at same time contributing
to economy of fuel.
-
The steam pressure recording indicators show the pressure which is to be
regulated as required until the stock is cooked or it is necessary to change the lye,
when the blow off pipe M at the bottom and steam pipe J at the top are opened.
The steam admitted by pipe J upon the material will force the lye out either to
waste or to a suitable vessel for recovery of the chemicals. The lye being undiluted
its treatment for the recovery of the chemicals will be comparatively inexpensive
and profitable.
The cooked stock is removed by the opening C, but before removal, and if
desired during the cooking process, the valve of pipe K may be opened to admit
steam below the stock for lifting and agitating the mass. This may be continued
for a suitable length of time, and to obtain more effective action a disc valve L,
Figure 5, faced with rubber is provided to close the pipes a in heater B to be
operated from the outside by a tube valve screw OPQ, and thereby cause the
steam to force the lye through the mass instead of through the pipes a.
The apparatus described is adapted for treating all materials used for paper, the
process being varied as required, the work being done rapidly and effectually, and
with a saving of time, labor, heat, and chemicals.
This apparatus may also be used for cooking food for cattle.
Having described the nature of the said Invention, and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
hereinbefore in part recited Letters Patent is,—

page_text: provided with a false bottom and furnishing and emptying valves or gates, and
the closed steam heater B combined for use and provided with the separate steam
supply pipes, substantially as shown and described.
2nd. In apparatus for boiling or digesting paper stock. the cylindrical steam
heater B provided with longitudinal tubes a and pipes H and N for connection
with a steam generator combined with digestor A having perforated false bottom E,
substantially as described and for the purposes set forth.
3rd. The hinged valve or gate D provided with clamps e combined with the
paper stock digestor A, substantially as described and for purposes set forth.
4th. The tie rod G provided with expansion socket W combined with the closed 1
cylindrical digestor A having heads b, 6, substantially as described and for purposes
set forth.
5th. The branch steam pipe J in combination with digestor A and discharge
pipe M, substantially as described and for the purposes set forth.
6th. The branch steam pipe H in combination with digestor A. and heater B, 1
substantially as described and for the purposes set forth.
7th. The branch steam pipe K in combination with digestor A and perforated
false bottom E, substantially as described and for the purposes set forth.
8th. The disc valve L in combination with digestor A, heater B, steam pipe K,
substantially as described and for the purposes set forth..
9th. The pipe V in combination with digestor A and a recording steam gauge,
substantially as described and for the purposes set forth.
10th. The pipe V in combination with heater B, tubes a, and a recording steam
gauge, substantially as described and for the purposes set forth.
11th. The pipes U and V with the recording steam gauges in combination with
a recording steam gauge on the generator, substantially as described and for
purposes set forth.
12th. The condensed steam pipe N in combination with heater B and steam
generator, substantially as described and for the purposes set forth.
13th. The application of indirect steam heat in closed digestor A through the
medium of the heater B in combination with steam generator for digesting or
cooking paper stock, substantially as described and for the purposes set forth.
In witness whereof, I, the said Alexander Melville Clark, have hereunto set
my band and seal, this Twenty fourth day of September, A.D. 1881.
35 AT ADIZ