Improvements in and Connected with Boilers or Digesters Lined with Lead or other Acid Resisting Metal or Alloy, Especially Suited for Use in Preparing Paper Making Materials or for Analogous Purposes.
Year: 1888

page_text: Date of Application, 11th Oct., 1888
Complete Specification Left, 12th Aug., 1889-Accepted, 5th Oct., 1889
PROVISIONAL SPECIFICATION.
Improvements in and Connected with Boilers or Digesters Lined
with Lead or other Acid Resisting Metal or Alloy, Especially
Suited for Use in Preparing Paper Making Materials or for
Analogous Purposes.
We, ISAAC SHIMWELL MCDOUGALL, and JAMES THOMAS MCDOUGALL, both of
Irk Vale, Chadderton, near Manchester, in the County of Lancaster, Manufacturing
Chemists, do hereby declare the nature of this invention to be as follows:-
This Invention has for its object to provide a boiler or digester lined with lead or
other acid resisting metal or alloy which is much less liable to get out of order than
are those hitherto generally employed.
We will for simplicity refer to the lining and other parts as being of lead it being
understood that we include any other suitable acid resisting metal or alloy.
The improved boiler or digester made according to this Invention enables the
materials to be acted upon in a very efficient manner and admits of ready discharge
of its contents.
We prefer to make the boiler or digester with a main body part of iron or steel
plates and of a cylindrical form and at its lower end it terminates in an inclined or
funnel shaped portion. The body part and the funnel shaped lower end are encased
in a jacket which forms a steam space which is entirely separate from and has no
communication whatever with the interior of the boiler or digester so that none of
the acid contained therein can get into the space enclosed by the jacket. The boiler
or digester is lined with lead and the space between the jacket and boiler or digester
has means for the inlet of steam and an outlet preferably provided with a steam
trap.
By admitting steam into the jacket the pressures and temperatures inside and
outside the boiler or digester can be equalized or maintained at such equal or approxi-
mately equal degrees that the lead lining does not become injured by any difference
between inside and the outside temperatures and pressures on the boiler or digester
whilst as there is no communication between the jacketted space and the interior
of the boiler or digester the jacket is not injured by acid. A pipe may pass down
inside the boiler or digester opening preferably near the bottom of the body part at
the centre thereof and this can be used to admit steam or water. The outlet attach-
ment which forms the termination of the funnel shaped end may be solid except for
the outlet passage through it or it may be hollow and be jacketted the jacket space
communicated with the main jacketted space when owing to the jacket enveloping the
whole of the body part and funnel shaped end at the bottom part the whole of the
mass in the boiler or digester is thoroughly heated. The top of the boiler may be
covered by a conical top provided with a safety valve and a gauge glass. There may
be spy holes in the jacket provided with tightly fitted covers by reinoving which the
outside of the boiler or digester may be examined when desired. As regards the lead
lining we prefer to attach or connect it as follows:-Before the plates of the main
body part are placed together we take plates of lead fitted to cover over and fit
completely the surface of the inner sides of the outer plates and so arranged to lap
over each other that none of the outer metal is exposed to the contents of the boiler
or digester. This may be done in the following manners. If the joints be "butt
strip joints" then the outer "butt strip plate" can be made of lead or if the outer
"butt strip plate" be made of iron or steel the inner surface of the "butt strip
plate' can be covered with lead. The lead forming the lining of the boiler or
digestor may either be turned over the edges of the iron or steel plates or their
meeting edges may be covered by an inner strip of lead either at back or front
"

page_text: or both. If the joints be those known as "lap joints" then the lead may be lapped
over the iron or steel plates at the edges thereof so that the edges of the lining
come to outside the plates. This may be done with all the plates or with only
such of them as have their edges exposed within the boiler or vessel to the action
of the acid those which have their edges outside being simply covered on their
interior surface with lead.
The manholes rims and covers and mounting blocks or like fittings may be made
of acid resisting metal, but if made of iron or steel they can be covered with lead as
described with regard to the plates and where rivetted the flange or surface of the
mountings may be provided with countersunk rivet holes so that the rivet head can
be level with the surface or flange face leaving a suitable surface for making a tight
joint by employing suitable packing and connections.
The rivets or bolts employed in the construction of the boiler or digester may be
made of acid resisting metal.
If plates of large dimensions be employed it may be desirable after the plates are
shaped and fitted to rivet the plates together by a number of rivets made of lead and
situated at suitable distances from the outer edges of the plates as a means of
strengthening the combined metal plates between the joints to hold the plates in closer
contact. By the method above described an iron or steel boiler or digester is con-
structed having all its inner surface of lead and capable of having its joints readily
and efficiently caulked and of resisting the action of acid with the further advantages
of economy strength and durability.
If preferable a covering of paint or a suitable material to form a packing
may be applied between the surfaces of the plates before the parts are placed
together..
The jacket arrangement and the method of securing or connecting the lead lining
may be used either separately or combined.
In order to prevent damage to the lead lining owing to the vapourization of water
which may leak to between the inner shell and lining we may perforate the shell (but
not the lead lining) at intervals and over these perforations we place and secure a
tube or hollow piece extending through the steam space and opening outside the
jacketting where it may pass through a hole for giving admittance for inspection.
The said hole may be closed by a cover which can pass over the tube or hollow piece
and be secured tightly by a nut passing onto the tube or hollow piece. Or other
suitable means may be employed for securing the covers and tubes or hollow pieces.
The said tubes or hollow pieces may thus constitute strengthening stays. Any leakage
to between the inner shell and lead lining will be detected owing to escape by the pipes
or hollow pieces by which also vapour will escape from between the shell and the
lining before it causes any damage.
D
11
J. H. JOHNSON & Co.
47, Lincoln's Inn Fields, Agents.
COMPLETE SPECIFICATION.
Improvements in and Connected with Boilers or Digesters Lined
with Lead or other Acid Resisting Metal or Alloy, Especially
Suited for Use in Preparing Paper Making Materials or for
Analogous Purposes.
We ISAAC SHIMWELL MCDOUGALL and JAMES THOMAS MCDOUGALL both of Irk
Vale Chadderton near Manchester in the County of Lancaster Manufacturing Chemists
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 :-
This Invention has for its object to provide a boiler or digester lined with lead or
other acid resisting metal or alloy which is much less liable to get out of order than
are those hitherto generally employed.

page_text: We will for simplicity refer to the lining and other parts as being of lead it being
understood that we include any other suitable acid resisting metal or alloy.
The improved boiler or digester made according to this Invention enables the
materials to be acted upon in a very efficient manner and admits of ready discharge
of its contents.
We will describe this invention with reference to the accompanying drawings.
Figure 1 of which represents in vertical section a boiler or digester made according
to this Invention. Figure 2 shows a mode of forming the joints. Figure 3 is a
vertical section and Figure 4 is a plan of a modified form of boiler or digester.
Figure 5 is an enlarged section of an alternative form of joint for a boiler or
digester and Figure 6 shows the Invention as applied to a spherical boiler or
digester.
Referring first to Figure 1 we prefer to make the boiler or digester with a main
body part A of iron or steel plates and of a cylindrical form and at its lower end
it terminates in an inclined or funnel shaped portion B.- The body part A and the
funnel shaped lower end B is or are encased in a jacket C which forms a steam
space D which is entirely separate from and has no communication whatever with
the interior E of the boiler or digester so that none of the acid contained therein
can get into the space enclosed by the jacket C. The boiler or digester is lined
with lead and the space between the jacket and boiler or digester has an inlet for
steam as shown for instance at F and an outlet (preferably provided with a steam
trap) for instance as shewn at G.
By admitting steam into the space between the jacket and the body of the boiler or
digester the pressures and temperatures inside and outside the boiler or digester can
be equalized or maintained at such equal or approximately equal degrees that the lead
lining H does not become injured by any difference between the inside and outside
temperatures and pressures on the boiler or digester whilst as there is no communica-
tion between the jacketted space and the interior of the boiler or digester the jacket
is not injured by acid. A pipe may (as shewn at I) pass down inside the boiler or
digester opening preferably near the bottom of the body part at the centre thereof
and this can be used to admit steam or water or acid liquors. The outlet attachment J
which forms the termination of the funnel shaped end may be solid except for the
outlet passage through it or it may be hollow and be jacketted the jacket space com-
municating with the main jacketted space when owing to the jacket enveloping the
whole of the body part and funnel shaped end at the bottom part and its outlet attach-
ment the whole of the mass in the boiler or digester is thoroughly heated. The top
of the boiler may be covered by a conical top A³ with an inlet opening covered by
a cover A in which (or in other suitable part) may be a safety valve a and a gauge
glass may be used as at K to enable the height of the liquor in the boiler or digester
to be seen so that the said height may be regulated as required. There may be spy
holes in the jacket as at q Figure 5 provided with tightly fitted covers by removing
which the outside of the body part of the boiler or digester proper may be examined
when desired. As regards the lead lining we prefer to attach or connect it as follows.
Before the plates of the main body part are placed together we take plates of lead H
(see Figures 2 and 5) fitted to cover over and fit completely the surface of the inner
sides of the outer plates A and so arranged to lap over or abut against each other
that none of the outer metal is exposed to the contents of the boiler or digester.
This may be done in the following manners. If the joints be "butt strip joints'
(see Figure 2) then the outer "butt strip plate" can be made of lead or if the
outer "butt strip plate" be made of iron or steel the inner surface of such "butt
strip plate" can be covered with lead. The lead forming the lining of the boiler
or digester may either be turned over the edges of the iron or steel plates as shewn
in dotted lines at h or their meeting edges may be covered by an inner strip of
lead 1.
If the joints of the iron or steel plates be
lead may be lapped over the iron or steel
edges of the lining come to outside the plates.
وو
those known as "lap joints" then the
plates at the edges thereof so that the
This may be done with all the plates

page_text: .
or with only such of them as have their edges exposed within the boiler or vessel
to the action of the acid those which have their edges outside being simply covered
on their interior surface with lead. Figure 5 shows the joints made by angling
the plates of iron or steel the lead plates being turned over these flanges and the
flanges being bolted together preferably with a caulking ring m of lead between as
.shown.
The manholes rims and covers and mounting blocks or like fittings may be made
of acid resisting metal, but if made of iron or steel they can be covered with lead
as described with regard to the plates and where rivetted the flange or surface of
the mountings may be provided with countersunk rivet holes so, that the rivet heads
can be level with the surface or flange face of the part to which they are attached
leaving a suitable surface for making a tight joint by employing suitable packing and
connections, as shown in the manhole Figure €.
The rivets or bolts employed in the construction of the boiler or digester may be
made of or covered with acid resisting metal.
If plates of large dimensions be employed it may be desirable after the plates
are shaped and fitted to rivet the plates together by a number of rivets as at n² made
of lead and situated at suitable distances from the outer edges of the plates as a
means of strengthening the combined metal plates between the joints to hold the
plates in closer contact. This is shown in Figure 3. By the methods above described
an iron or steel boiler or digester is constructed having all its inner surface of lead
and capable of having its joints readily and efficiently caulked and of resisting the
action of acid with the further advantages of economy strength and durability.
If preferable a covering of paint or a suitable material to form a packing may be
applied between the surfaces of the plates before the parts are placed together.
The jacket arrangement and the method of securing or connecting the lead lining
may be used either separately or combined.
In order to prevent damage to the lead lining owing to the vaporization of water
which may leak to between the inner shell and lining we may perforate the shell (but
not the lead lining) at intervals as shown at n (refer to Figure 3 and to the enlarged
details Figures 2 and 5) and in cases where a steam jacket encloses the whole of
the shell we place over these perforations a tube or hollow piece Fig. 1 extending
through the steam space enclosed by the jacket and opening outside the jacketting
where it may pass through a plate covering a hole in the jacket for giving admittance
for inspection. The said tube or hollow piece may either be left open at its outer
end or be closed by a cover which can pass over the tube or hollow piece and be
secured tightly by a nut passing onto the tube or hollow piece. Or other suitable
means may be employed for securing the covers and tubes or hollow pieces. The
said tubes or hollow pieces may thus constitute strengthening stays. Any leakage
to between the inner shell and lead lining will be detected owing to escape by the
pipes or hollow pieces by which also vapour will escape from between the shell and
the lining before it causes any damage.
We have described the steam jacket as being one space but in cases where the
pressure is excessive or the boilers or digesters are of large diameters the steam
jacketting may be constructed in sections so as to form a series of pockets or
spaces Pinstead of a single jacket enveloping the whole of the inner casing or
fibre boiler. This is shown in Figures 3, 4, 5 and 6. By this means the total
pressure acting on the outside of the boiler or digester is reduced while the pockets
form stays which very materially strengthen the false boiler against collapse.
Figures 3 and 4 show how these pockets may be arranged in the form of a series
of belts running circumferentially round the boiler in such a manner as to avoid
covering or overlapping the circumferential or longitudinal seams therein. Figure 4
shows each of these belts to consist of two pockets but they may be constructed of
one two three or more pockets if preferred while each or any of the pockets may
be fitted with sight holes and inspection doors if desired. For giving additional
strength the gaps between the pockets in each belt may be arranged to break joint
with those in the belts above or below as shown in Figure 4.

page_text: In Figure 5 one of the steam pockets is shown. In this case they are built up
against two rings of channel iron rivetted to the shell of the boiler or digester and
also to a circular covering plate p. In this covering plate closable sight holes q may
be provided at convenient intervals for inspection. By means of these channel iron
rings and flanged seams the internal body of the boiler or digester may be made
exceedingly strong and therefore may be constructed of large diameters and capable
of withstanding high pressures both internally and externally. The steam is supplied
by the pipe F with branches f to each pocket and the water of condensation is led off
from each pocket by pipes g leading to one common outlet G.
Figure 6 shows the method of arranging the steam jacket and pockets above
described applied to a boiler of the spherical shape revolving on trunnions.
The steam is admitted through one trunnion to suitable pipes for distribution to
the various pockets or chambers while the condensed water is drawn off by means of
suitable collecting pipes g through the opposite trunnion.
The methods above described enable wood fibre to be digested by the heat of steam
applied indirectly to the outside of the shell instead of being blown directly into the
interual boiler thus effecting great economy and efficiency in the manufacture but the
boilers or digesters made according to this invention may be used with internal
injection of steam or other agent as well as being externally heated.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
1. A boiler or digester lined with lead or other acid resisting metal or alloy the
said boiler or digester terminating at its lower end in a funnel shaped portion the
body and the said funnel shaped portion being encased in a jacket the interior of
which does not communicate with the interior of the boiler or digester the jacket
being provided with an inlet and an outlet substantially as and for the purposes
herein before described.
2. In combination with a boiler or digester arranged as claimed by the preceding
claiming clause a pipe passing down inside thereof and opening near to the bottom
thereof substantially as and for the purposes herein before described.
3. The arrangement and combination of parts constituting the boiler or digester as
herein before described and illustrated in Figure 1 of the accompanying drawings.
4. In boilers or digesters lined with lead or other acid resisting metal or alloy a
lining of the said materials having its edges turned over the body plates or with its
edges covered inside or outside or both with acid resisting material the joints being
made either as "butt" joints or as lap' joints substantially as herein before
described.
"
وو
5. In boilers or digesters lined with lead or other acid resisting metal or alloy
perforations in the shell and in the jacket and tubes or hollow pieces forming com-
munication from between the lining and body plates to the exterior of the boiler or
digester substantially as herein before described.
6. In combination with boilers or digesters lined with lead or other acid resisting
metal or alloy a jacketting made in sections so as to constitute separate spaces or
pockets substantially as herein before described and illustrated by Figures 3, 4, 5 and 6
of the accompanying drawings.
7. The arrangement and combination of parts constituting the boiler or digester as
herein before described and illustrated in Figures 3 and 4 of the accompanying
drawings.
8. The arrangement and combination of parts constituting the boiler or digester
herein before described and illustrated in Figure 6 of the accompanying drawings.
Dated this 19th day of August 1889
J. H. JOHNSON & Co.,
Agents.