Improvements in Water Tube Boilers.
Year: 1899

page_text: Date of Application, 17th May, 1899
Complete Specification Left, 19th Feb., 1900-Accepted, 24th Mar.,
1900
PROVISIONAL SPECIFICATION.
Improvements in Water Tube Boilers.
I, JOHN ISAAC THORNYCROFT, F.R.S., of the Firm of John I. Thornycroft & Co.,
Church Wharf, Chiswick, London, W., Marine Engineers and Shipbuilders, do
hereby declare the nature of this invention to be as follows;-
This invention has reference to water tube boilers of the so-called "Daring"
type (see Thornycroft's Patent No. 17809/90) wherein inter alia an, upper
steam and water vessel is connected to three lower water vessels by groups of
bent water tubes so disposed that some of them form flues in which other tubes
are located and through which the products of combustion escaping from the
fire boxes formed by and between the groups of tubes, pass on their way to the
chimney or uptake.
In such boilers it sometimes happens, especially when they are of small height,
that the hot gases are not uniformly distributed throughout the whole length of
the flues but tend to take a short path to the chimney with the result that the
whole of the heating surface of the tubes is not utilized to the greatest advantage.
Now this invention has for object to prevent or mitigate this drawback for
which purpose some of the tubes within each inner or outer flue, or in each of
the inner and outer flues, are arranged to form, except at their ends, one or more
close walls of tubes that serve to divide the flue lengthways into two or more
compartments that communicate with each other at their upper and lower
ends through passages formed by and between the upper and lower end portions
of the tubes after the manner of the inlet and outlet, passages ordinarily formed
between the upper and lower ends of the tubes constituting the inner and outer
walls of the flue, the arrangement being such that hot gases on entering the
lower end of the flue through the lower passages in that wall thereof which is
next the fire box, will divide, a portion of them passing up the compartment
of the flue next the fire box and the remaining portion passing through the lower
passages in the intermediate close wall or walls of tubes and rising through the
other, compartment or compartments of the flue, the streams of hot gas upon
reaching the upper ends of the compartments flowing through the passages
left between the upper ends of the intermediate wall or walls of tubes and the
inner or outer walls, or inner and outer walls of the flues, according to the
particular design of the boiler, and thence passing to the chimney. The height
of the passages through the upper and lower portions of the intermediate close
wall or walls of tubes can be varied to suit requirement. The height of the
lower passages will usually be less than that of the lower passages in that wall
The invention can
of the corresponding flue which is next the firebox.
be applied in connection with various arrangements of water tubes forming flues
at one or at each side of the fire box or each fire box of the boiler.
In one arrangement of boiler of the kind referred to, the bent water tubes
0 that connect the upper steam and water vessel to the lower central water vessel,
enter the former vessel at each side thereof and are arranged in rows whereof
the two inner rows (i.e. those nearest to the vertical plane of the longitudinal

page_text: centre of the boiler) and the two outer rows (i.e. those next to the fire box) are
bent to form (excepting as to their ends) tube walls which constitute flues wherein
the remaining tubes are arranged in rows, the two inner walls of the two flues
having between them a central space or flue in connection with the chimney.
Each of the outer lower water vessels is connected with the upper vessel, also by
several rows of tubes whereof the two outer rows and the two inner rows are
made to form (excepting as to the ends of the tubes) walls of a flue within which
the remaining tubes are arranged in rows. The outer wall of each inner flue,
and the inner wall of each outer flue meet at a suitable distance above the fire
grate and the lower portions of the tubes constituting these respective walls
are so arranged as to provide passages between the wall tubes whereby products
of combustion can enter the respective flues up which they flow. The upper
portions of the tubes of both walls of each inner flue and those of the inner wall
of each outer flue are arranged to afford passages between those portions of the
said tubes whereby the upper ends of both flues communicate with each other and
with the central space or flue between the two inner flues. Within each inner
Hue, and also it may be within each outer flue, is formed an intermediate close
wall of tubes as and for the purpose herein before described, the passages in the
lower portion of each such wall being usually of less height than the inlet
passages in the adjacent wall of the flue and those in the upper portion of the said
intermediate wall being of about the same length as those in the upper portions
of the flue walls. The arrangement is such that the hot gases ascending the
separate flues of each fire box re-unite at the top and thence flow through the
upper passages of the inner walls of the inner flues to the central space or flue and
thence to the chimney. The upper vessel is or may be connected to the lower
central vessel by downtake tubes extending through the central space or flue, and
to the lower outer vessels by separate external downtake tubes.
1, JOHN ISAAC THORNYCROFT, F.R.S., of the Firm of John I. Thornycroft & Co.,
Church Wharf, Chiswick, London, W., Marine Engineers and Shipbuilders, 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 reference to water tube boilers of the so-called "Daring"
type (see Thornycroft's Patent No. 17809 of 1890) wherein inter alia an upper
steam and water vessel is connected to three lower water vessels by groups of
bent water tubes so disposed that some of them form flues in which other tubes
are located and through which the products of combustion escaping from the
fire boxes formed by and between the groups of tubes, pass on their way to the
chimney or uptake.
In such boilers it sometimes happens, especially when they are of small height,
that the hot gases are not uniformly distributed throughout the whole length of
the flues but tend to take a short path to the chimney with the result that the
whole of the heating surface of the tubes is not utilized to the greatest advantage

page_text: Now this invention has for object to prevent or mitigate this drawback for
hich purpose some of the tubes within each inner or outer flue, or in each of
he inner and outer flues, are arranged to form, except at their ends, one or more
lose walls of tubes that serve to divide the flue lengthways into two or more
eparate compartments that communicate with each other at their upper and lower
nds through passages formed by and between the upper and lower end portions
f the tubes after the manner of the inlet and outlet passages ordinarily formed
etween the upper and lower ends of the tubes constituting the inner and outer
valls of the flue, the arrangement being such that hot gases on entering the
ower end of the flue through the lower passages in that wall thereof which is
ext the fire box, will divide, a portion of them passing up the compartment
of the flue next the fire box and the remaining portion passing through the lower
passages in the intermediate close wall or walls of tubes and rising through the
other compartment or compartments of the flue, the streams of hot gas upon
reaching the upper ends of the compartments flowing through the passages
eft between the upper ends of the intermediate wall or walls of tubes and the
inner or outer walls, or inner and outer walls of the flues, according to the
particular design of the boiler, and thence passing to the chimney. The height
of the passages through the upper and lower portions of the intermediate close
wall or walls of tubes can be varied to suit requirement. The height of the
lower passages will usually be less than that of the lower passages in that wall
of the corresponding flue which is next the fire box. The invention can
be applied in connection with various arrangements of water tubes forming flues
at one or at each side of the fire box or each fire box of the boiler.
The accompanying illustrative drawing shows in cross section one arrangement
of boiler of the kind referred to embodying the present invention.
The bent water tubes that connect the upper steam and water vessel a to the
lower central water vessel b, enter the former vessel at each side thereof and are
arranged in rows whereof the two inner rows c, d, (i.e. those nearest to the vertical
plane of the longitudinal centre of the boiler) and the two outer rows e f (i.e. those
next to the fire box) are bent to form (excepting as to their ends) tube walls
which constitute flues 9 wherein the remaining tubes are arranged in rows,
the two inner walls of the two flues y having between them a central space or
flue in connection with a chimney i at the end of the boiler as in the con-
struction of boiler described in my said former specification. Each of the outer
lower water vessels ; is connected with the upper vessel a also by several rows
of tubes whereof the two outer rowsk and the two inner rows m'n are made to
form (excepting as to the ends of the tubes) walls of a flue o within which the
The outer wall of each inner
remaining tubes of the group are arranged in rows.
flue g, and the inner wall of each outer flue o meet at p at a suitable distance
above the fire grate , and the lower portions of the tubes constituting these
respective walls are so arranged, as shown, as to provide inlet passages between
the wall tubes whereby products of combustion from each fire-box s can enter
the respective flues g and up which they flow. The upper portions of the
tubes cand e f of both walls of each inner flue g and those m n of the inner
wall of each outer flue o are arranged to afford passages t between such portions
of the said tubes whereby the upper ends of both flues g and o communicate
with each other and with the central space or flue h.
Within each inner flue g, and also it may be (as shown) within each outer
flue o, is formed an intermediate close wall of tubes as and for the purpose
herein before described, the passages in the lower portion of each such wall
being usually of less height than the inlet passages r in the adjacent wall of the
flue and the passages in the upper portion of the said intermediate wall u
being of about the same length more or less, as those, viz. t, in the upper portions
of the flue walls. As will be seen the arrangement is such that the hot gases*
will
upon entering the flues g and o from the fire boxess through the passages,
divide, part passing up the compartments of the flues formed by and between

page_text: the tube walls next the fire boxes and the intermediate tube walls u, and part
passing through the passages in such intermediate tube walls and passing up
the compartments of the flues formed by and between such intermediate tube
walls and the walls, of the flues farthest from the combustion chambers. The
gases thus divided and caused to ascend the adjacent compartments of the flues g
and o, of each fire box s, reunite at the top through the passages w and thence
flow through the upper passages of the inner walls of the outer flues o and
both walls of the inner flues g to the central space or flue h and thence to the
chimney. The upper steam and water vessel a is or may be connected to the
lower central vessel by downtake tubes a extending through the central space
or flue h, and to the lower outer vessels by separate external downtake tubes y,
as shown by dotted lines, but other arrangements of downtake tubes can be used
for connecting the upper vessel to the lower vessels, if desired.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is―
1. A water tube boiler of the "Daring" type wherein some of the tubes in
each inner or outer flue g or o or in each of the inner and outer flues are arranged
close together so as to form, except at their ends, one or more close walls of
tubes that serve to divide the flue lengthways into two or more separate compart-
ments that communicate with each other at their upper and lower ends through
passages wand v formed by and between the upper and lower end portions of
the tubes, the arrangement being such that hot gases on entering the lower end
of the flue through the lower passages in that wall thereof which is next the
fire-box, will divide, a portion of them passing up the compartment of the flue
next the firebox and the remaining portion passing through the lower passages v
in the intermediate close wall or walls of tubes and rising through the other
compartment or compartments of the flue, the streams of hot gases upon reaching
the upper ends of the compartments flowing through the passages left between
the upper ends of the intermediate wall or walls of tubes and the inner or outer
or inner and outer walls of the flues and thence passing to the chimney, sub-
stantially as described for the purposes specified.
2. A water tube boiler of the "Daring" type wherein the tubes forming
the walls of the inner and outer flues and the tubes, or some of them, located
within such flues are bent and arranged substantially as hereinbefore described
with reference to and shown in the drawings annexed, the arrangement being
such that the said flues are divided into compartments such as described within
which the hot gases pass upward as set forth.
3. The improved construction hereinbefore described with reference to and
shown in the drawings annexed of water tube boilers of the kind referred to.
Did this 10th day of February 1900.
JATTE
LILID JULIA
For the Applicant,
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.