Improvements in Double-tube Boilers, Evaporators, and other Heat Exchangers.
Year: 1895

page_text: Date of Application, 7th Mar., 1895
Complete Specification Left. 25th Nov.. 1895-Accepted, 25th Jan., 1896
PROVISIONAL SPECIFICATION.
Improvements in Double-tube Boilers, Evaporators, and other
Heat Exchangers.
We, KENNETH DAVID NOBLE, of 143, East Princes Street, Helensburgh, in
the County of Dumbarton, North Britain, Engineer, and JOHN IRVING, Of
Avenue End, Cardross, in the same county, Engineer, do hereby declare the
nature of this invention to be as follows, that is to say :-
Our said invention comprises improved constructions applicable with economy
and efficiency for boilers, evaporators, and other heat exchangers, such as fresh-
water distillers, condensers, and the like. In our said improved constructions
double tubes are used, that is pairs of tubes with one of each pair extending
through the other and water or other liquid being between the inner and outer
tube. Our invention also comprises improved devices for fastening the double
tubes in their places.
A steam boiler constructed according to our invention comprises a stack of
inclined double tubes the ends of which are fixed in higher and lower water chests,
the upper end of the higher water chest being in communication with one or more
still higher steam drums or cylinders, placed along or at right angles to the highor
water chest, and connected by downward circulation tubes to a lowly placed
horizontal tube or cylinder communicating with the lower part of the lower water
chest. The furnace is placed under the stack of double tubes, the fire gases
passing up amongst the tubes and acting on the outsides of the larger tubes of each
pair. From the space above the stack of double tubes the fire gases pass to the
back of the lower water chest and thence through the inner tubes of each pair of
double tubes to a smoke box or uptake communicating with the chimney or
funnel.
The water chests are made of steel or iron boiler plate, each comprising a single
folded plate forming both innor and outer side, or made up of two or more plates
flanged and riveted together. The two plates of each water chest are both tube
plates, and the tube joints and other parts are formed so that both tubes of each
pair can be inserted from the outside of one water chest, proferably the higher one.
The sides and other parts of the space containing the details hereinbefore described
may be closed or partly closed by water tubes, or by firebrick or other suitable
incasement.
Instead of the fire gases acting first on the outsides of the outer tubes, they may
be made to pass first through the inner tubes and afterwards to pass in contact
with the outsides of the outer tubes.
In one modification of our improved joints for connecting the double tubes to
the inner and outer plates of each water chest, the outer tube extends through
both plates of each chest and is screwed externally so as to receive nuts on both
the inner and outer sides of the inner tube plate of ench chest, nud so as to receive
a nut on the outside of each outer tube plate. The outer tube is also screwed
internally at each outer end to receive a pair of glands or short tubes which hold
the ends of the inner tube. The part of the outer tube within each water chest
has holes formed in it for the passage of fluid into and from the chest from and
into the space between the two tubes. The part of the larger tube extending
through the higher water chest is made slightly larger than the part extending
through the lower water chest.

page_text: In other modifications the outer tube torminates a little within the inside of each
water chest, whilst a short tube screwed to the inside or outside of the outer tube
extends through each outer tube plate and has the inner tube secured in its outer
end by one or two screw glands. The short tube has the necessary communicating
holes made in it. Or tho additional short tube may be dispensed with, each end of
the inner tube being secured by a pair of screwed glands fitted to the outer tube
plate in a hole which is large enough for passing the outer tube through into its
place when the glands are absent. An elongated or tubular nut may be screwed
upon the outer tube on the inside of the inner tube plate, this tubular nut having
communicating openings formed in it so as not to obstruct the fluid currents.
the inner tube end may be secured by a ring screwed upon it and into the hole in
the outer tube plate jam nuts being applied to both parts.
And
In all the modifications of tube joints or fastenings the outer tubes screw into
internal screw threads formed in the tube-plate holes.
In some cases double tubes may be used for the downward return currents of
water, such downward currents flowing through the inner tubes, whilst the outer
tubes being acted by the fire gases will cause an upward flow in the space between
the two tubes.
The tubes for the downward currents, with or without inner tubes, are fixed in
their places by having each one end screwed into a nipple formed on or bolted to
the drum, pipe, or casing, whilst the other end is screwed upon a short tube which
is itself screwed into a nipple formed on or bolted to the opposite drum, pipe or
casing. The screw threads of the connections are made of different pitches
admitting of the parts being put together or separated without disturbing the
positions of the parts connected by the tubes.
Dated this Sixth day of March 1895.
EDMUND HUNT,
Applicants' Agent.
Improvements in Double-tube Boilers, Evaporators, and other
Heat Exchangers.
We, KENNETH DAVID NOBLE, of 143, East Princes Street, Helensburgh, in
the County of Dumbarton, North Britain, Engineer, and JOHN IRVING, Of
Avenue End, Cardross, in the same county, 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, that is
to say :-
Our said invention comprises improved constructions applicable with economy and
efficiency for boilers, evaporators, and other heat exchangers, such as fresh-water
distillers, condensers, and the like. In our said improved constructions double
tubes are used, that is pairs of tubes with one of each pair extending through the
other, and water or other liquid being between the inner and outer tube. The
tubes extend between two water chests formed of steel or iron boiler plate,
the inner sides of these water chests forming tube plates in which the outer tubes
are fixed, and the outer sides forming tube plates in which the inner tubes are fixed.
Our invention also comprises improved devices for fastening the double tubes in
their places.
Two modifications of boilers, as made according to our invention, together with
some details of the same are shown on four accompanying sheets of explanatory
drawings, Figures, 1, and 2, on Sheet, 1, thereof being respectively a sectional end
elevation and a longitudinal vertical section of one modification, and Figures, 3,
and 4, on Sheet, 2, similar views of another modification. Figures, 5, 6, 7, 8, and 9,

page_text: on Sheet, 3, and Figures, 10, and 11, on Sheet, 4, are longitudinal sections of
details. In these drawings the same reference letters and numerals are used to-
mark the same or liko parts wherever they are repeated.
A steam boiler constructed according to either of the modifications shown in
Figures, 1, 2, 3, and 4, of the drawings comprises a stack, A, of inclined double-
tubes the ends of which are fixed in a higher water-chest, B, and a lower water
chest, C, being in communication with one or it might be more still higher steam
drums or cylinders, D, placed (as in Figures, 1, and 2.) along or (as in Figures, 3,
and 4,) at right angles to the higher water chest, and connected by downward
circulation tubes, E, to a lowly placed horizontal tube or cylin ler, G, communicating
with the lower part of the lower water chest. The furnace, H, is placed under the
stuck, A, of double tubes, the fire gases passing up amongst the tubes, and acting--
on the outsides of the larger tubes, A. 1, of each pair. From the space, J, above-
the stack, A, of double tubes, the fire gases pass to the back of the lower water-
chest, C, and thence through the inner tubes, A 2, of each pair of double tubes to-
a smoke box or uptake, K, communicating with the chimney or funnel.
The water chests, B, and C, are made of steel or iron boiler plate, each com-
prising a single folded plate forming both the inner side, BI, and the outer-
side, B2, or each may be made up of two or more plates flanged and riveted
together. The two plates, B 1, and B 2, of each water chest, B, and C, are both
tube plates, and the tube joints and other parts are formed so that cach pair of
tubes, A 1, and A 2, can be inserted from the outside of one water chest, preferably
the higher one. The sides and other parts of the space, containing the details.
bereinbefore described, may be closed or partly closed by water tubes, E, aud
firebrick, M, (as shown in Figures, 1, and 2) or by firebrick, M, only (as shown in.
Figures, 3, and 4) or other suitable incasement.
Instead of the fire gases acting first on the outsides of the outer tubes, A I, they
may be made to pass first through the inner tubes, A. 2, and afterwards to pass in.
contact with the outsides of the outer tubes. We however prefer to have the fire
gases proceeding as firstly herein before described, as with the somewhat cooler-
gases acting on the inner tubes, their length being greater than that of the outer-
tubes on which the hotter gases act, will tend to equalise the elongations of the two-
tubes by the heat.
In one modification of our improved joints (shown in Figure, 5) for connecting-
the double tubes, A 1, and A. 2, to the inner plate, B1, and outer plate, B 2, of
each water chest (B) and (C) the outer tube, A 1, extends through both plates of
each chest, and is screwed externally so as to receive nuts, N, N 1, on both the
inner and outer sides of the inner tube plate of each chest, and so as to receive a
uut, N 2, on the outside of each outer tube plate. The outer tube, A 1, is also-
screwed internally at each outer end to receive a pair of glands, P, P1, (or it.
might be short tubes) which hold the ends of the inner tube, A.2. The part of the
outer tube, A 1, within each water chest, (B, C,) has holes, Q, formed in it for the.
passage of fluid into and from the chest, from and into the space between the two-
tubes, A 1, and A 2. The part of the larger tube, A 1, extending through the
higher water chest (B) is made slightly larger than the part extending through the -
lower water chest (C).
In another modification shown in Figure, 6, the outer tube, A 1, terminates a
little within the inside of each water chest whilst a short tube, R, scrowed to the
outside (or inside) of the outer tube extends through each outer tube plate, B 2, .
and has the inner tube, A 2, secured in its outer end by two glands, P, and P 1,
(as shown at one side of the modification) or by a gland, P 1, and ferrule, R 3, as.
shown at the other side. The short tube, R, has the necessary communicating
holes, Q, made in it. In some cases (as shown in Figures, 7, and 8) the part of the
short tube, R, extending through the outer tube plate, 132, is screwed externally
and internally being provided externally with a nut, N 2, aud internally with a..
gland, P, to hold the inner tube, A 2, aud to screw down on metal or other packing.
rings, S, between the inner tube and tho short tube. The additional short tube, R.,.

page_text: may be dispensed with, each end of the inner tube, A 2, being secured by a pair of
screwed glands, P, aud, P 1, (as shown in Figure 9) fitted to the outer tube
plate, B2, in a hole which is large enough for passing the outer tube, A I, through
into its place when the glands are absent. In this modification the tube plates
may be connected by ordinary screw stays placed where required. Or the inner
tube end (A 2) may if desired be secured by a ring (not shown) screwed upon it
and into the hole in the outer tube plate (B 2) jam nuts bring applied to both
parts.
In all the modifications of tube joints or fastenings the outer tubes, A 1, serow
into internal screw threads formed in the tube-plate holes.
In some cases double tubes may be used for the downward return currents of
water, such downward currents flowing through the inner tubes, whilst the outer
tubes being acted on by the fire gases will cause au upward flow in the space
between the two tubes.
The tubes, E, for the downward currents, with or without inner tubes, 1, and
whether made with bends (as shown in Figure, 10) or straight (as shown in
Figure, 11) are fixed in their places by having their ends screwed into nipplea, T,
bolted to (Figure, 10) or formed (Figure, 11) on the drum, pipe, or casing (G).
In the case of a curved tube (such as is shown in Figure, 10) each length of outer
tube, E, lins one end screwed into the nipple, T, on each drum or pipe, (G,) and tho
other end screwed or coupled by a nut, T 1, or both screwed and coupled by a
nut, T1, to a bent piece, T 2. In the case of the straight tube (shown in Figure, 11)
one end of the outer tube, E, is screwed into the nipple, T, while the other end is
screwed upon and coupled by a nut, T 1, to a short piece, T 3, which is screwed
into the nipple on the opposito drum, pipe, or casing. The outer tube, E, is
provided with a jam nut, T5, to screw down on to the nipple, T, at one end. The
inner tubes, E1, may be supported where necessary by distance pieces, E 3, and
any or both of their ends may be flared if desired. The screw threads, V, of tho
connections are made of different pitches admitting of the parts being put together
or separated without disturbing the positions of the parts connected by the tubes..
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. The improved combination of parts forming as a whole the double-tube boiler
shown in Figures, 1, and 2, of the accompanying drawings and substantially as
herein before described.
2. The improved combination of parts forming as a whole the double-tube boiler
shown in Figures, 3, and 4, of the accompanying drawings and substantially as
herein before described.
3. In double tube boilers, evaporators and other like heat exchangers, the fixing
of the tubes in tube plates forming the inner and outer sides of chests connected by
the tubes, substantially as herein before described.
4. The several modifications of fastenings for fixing double-tubes in tube plates
forming the inner and outer sides of chests, substantially as shown in Figures, 5
to 11, of the accompanying drawings and heroinbefore described.
Dated this Twenty-sixth day of November 1895.
EDMUND HUNT,
Applicants' Agent.