Improvements in Water Tube Steam Boilers
Year: 1896

page_text: Date of Application, 26th Nov., 1896
Complete Specification Left, 25th Sept., 1897-Accepted, 26th Nov., 1897
Improvements in Water Tube Steam Boilers,
I, JOHN ISAAC THORNYCROFT, F.R.S. of the Firm of John I. Thornycroft & Co. of
Church Wharf, Chiswick, W., Steam Yacht and Launch Builders, do hereby declare
the nature of this invention to be as follows:-
In water tube boilers of the kind in which the gases rise from the fire and pass
directly amongst the steam generating tubes it happens that owing to inequalities
in the thickness of the bed of fuel over different parts of the fire grate the combustion
there is unequal and that consequently at or near the base of the funnel or uptake
very active combustion is liable to occur with great loss of heat that should be utilized
in the generation of steam in the tubes.
Now my invention is intended to obviate or mitigate this serious disadvantage in
boilers of the kind referred to for which purpose I so construct and arrange the
furnace that the gases from the fuel placed on the various parts of the fire grate are
compelled to all pass through an opening or openings or passage or passages of
comparatively limited cross sectional area in such wise that the said gases
become more
or less intimately mixed and averaged in combustible quality before coming into
contact with the tubes or the main portions of the tubes in which circulates the
water to be heated and converted into steam. Such a construction may be carried
out in various forms.
According to one construction I interpose between the fire grate and the water
tubes above it, two or more partitions of suitable refractory material so arranged that
one overlaps another and a space or spaces is or are provided between the over-
lapping parts which space or spaces constitutes or constitute the opening or openings
or passage or passages of comparatively limited cross sectional area through which
all the gases from the fuel on the grate have to pass on their way to the tubes to be
heated.
Sometimes portions of the boiler tubes or some of them may extend downward
below the partitions so that the fire gases will come in contact with some portions of
the tube heating surface before passing through the opening or openings of
comparatively limited cross sectional area as aforesaid.
According to another construction one or more of the partitions is or are formed
wholly or partly of tubes which may themselves constitute portions of the heating
surface of the boiler.

page_text: Improvements in Water Tube Steam Boilers.
I, JOHN ISAAC THORNYCROFT, F.R.S. of the Firm of John I. Thornycroft & Co. of
Church Wharf, Chiswick, W. Steam Yacht and Launch Builders, 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:—
In water tube boilers of the kind in which the gases rise from the fire and pass
directly amongst the steam generating tubes it occasionally happens that owing to
inequalities in the thickness of the bed of fuel over different parts of the fire grate,
the combustion there is unequal and that consequently at or near the base of the funnel
or uptake very active combustion is liable to occur with great loss of heat that should
be utilized in the generation of steam in the tubes.
Now my invention is intended to obviate or mitigate this serious disadvantage in
boilers of the kind referred to for which purpose I so construct and arrange the
furnace that the gases from the fuel placed on the various parts of the fire grate are
compelled to all pass through an opening or openings or passage or passages of com-
paratively limited cross sectional area in suchwise that the said gases becoine more or
less intimately inixed and averaged in combustible quality before coming into contact
with the tubes or the main portions of the tubes in which circulates the water to be
heated and converted into steam. Such a construction may be carried out in various
forms.
The accompanying drawings illustrate water tube boilers embodying my present
invention these boilers being respectively according to what are known as the
"Speedy" type (see my patent No. 1404 of 1885) and the "Daring" type (see my
patent No. 17809 of 1890).
Fig. 1 shows in cross section so much as is necessary, to illustrate a boiler of the
"Speedy" type with my present invention applied therein;
Fig. 2 shows a similar view of a boiler of the "Daring' type embodying my present
invention.
'
Fig. 3 corresponds to a longitudinal vertical section on either the line x x of Fig. 1
or of Fig. 2, and
Fig. 3 is a sectional plan on the line y y of Fig. 1.
The right hand portion of Fig. 1 corresponds to a section on the line A A of Fig. 3
so does the left hand portion of Fig. 2, whilst the left hand portion of Figure 1
corresponds to a section on the line B B of Fig. 3, and so also does the right hand
portion of Fig. 2.
According to the construction shown in these figures there are interposed between a
the fire grate 1 and the water tubes 2 above it, partitions 3, 4 of suitable refractory
material such as fire brick, these partitions, of which there may conveniently be
two "as shown, being so arranged that a space 5 is provided between their adjacent
ends, which space constitutes the opening or passage of comparatively limited cross
sectional area through which all the gases from the fuel on the grate have to pass on
their way to the tubes to be heated.
There may be more than two partitions so arranged as to form two or more open-
ings or passages of comparatively limited cross sectional area for the gases. Figs. 3B
and 3 show diaSrammatically two such arrangements in each of which there are three
partitions.
Sometimes portions of the boiler tubes or some of them, may extend downward

page_text: below the partitions or one of them, so that the fire gases will come in contact with.
some portions of the tube heating surface before passing through the opening or
openings 5.
Figs. 4, 5, and 6 are views (similar to Figs. 1, 2 and 3, respectively) showing an
arrangement of this kind in which the lower portions 2 of some of the tubes 2 are
bent and arranged to extend below the rearward partition 4.
Also, one or more of the partitions may be formed wholly or partly of tubes, which
may themselves constitute portions of the heating surface of the boiler. Figs. 7, 8
and 9 are views (similar to Figs. 1, 2 and 3, respectively) showing an arrangement of
this kind in which both of the partitions are formed wholly of tubes, by suitably
bending and arranging the lower portions of the tubes 2.
As the gases by virtue of their inertia tend to continue moving in the same
direction as that in which they leave the opening 5 it is desirable to guard against
the tubes 2 directly above the rear partition 4 being heated to a lesser degree than
those above the front partition 3. To this end in order to distribute the hot gases as
uniformly as possible amongst the tubes 2 after they have passed through the opening
or openings 5 the gas exit openings 6 arranged between the lower ends of the tubes 2
and leading to the flues 7 formned by and between some of such tubes, may be made
of different sizes so as to offer a varying obstruction to the passage of the hot gases
between the tubes. For this purpose in the constructions of boilers shown in the
drawings the openings between the lower ends of the tubes 2 at the front portion o
the boiler (and towards which openings the hot gases are directed on passing through
the opening 5) are made smaller as shown at 6 (see left hand side of Fig. 1, right
hand side of Fig. 2 and Fig. 3A) than the openings 6 between the lower ends of the
tubes at the rear portion of the boiler, (see right hand side of Fig. 1 left hand side
of Fig. 2 and also Fig. 3A) so that some of the hot gases will take a rearward course
to the said openings 6ª, as indicated by the arrow shown in dotted lines in Fig. 3.
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. In a water tube boiler of the kind hereinbefore referred to the arrangement in
combination of water tubes and a furnace or furnaces so constructed that the gases
from the fuel on various parts of the firegrate are compelled to all so pass through an
opening or openings, or passage or passages, of comparatively limited cross sectional
area that the said gases will become more or less intimately mixed and averaged ir
combustible quality before coming into contact with the tubes (or the main portions
thereof) in which circulates the water to be heated and converted into steam, as set
forth.
2. A water tube boiler in which there are provided between the fire grate and the
water tubes above it, two or more partitions of suitable refractory material sc
arranged that an opening or openings or passage or passages of comparatively limited
cross sectional area is or are formed between them through which all the gases from the
fuel on the grate have to pass on their way to the tubes to be heated, substantially
as described.
3. A water tube boiler of the kind referred to in the preceding claims in which
portions of the boiler tubes or some of them extend down below the partitions or one
of them so that the fire gases will come in contact with some portions of the tube
heating surface before passing through the opening or openings between the
partitions, substantially as described.
4. A water tube boiler of the kind referred to in claims 1 and 2 in which one or
more of the partitions is or are formed wholly or partly of tubes, substantially as
described.
5. My improved construction of water tube boilers having furnaces with partitions
arranged substantially as hereinbefore described with reference respectively to and
llustrated in Figs. 1 and 3, in Figs. 2 and 3; in Figs. 4 and 6; in Figs. 5 and 6;

page_text: in Figs. 7 and 9 and in Figs. 8 and 9 of the accompanying drawings, or modified a
set forth.
Dated this 26th day of September 1897.
For the Applicant,
W. LLOYD WISE,
46 Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.