Improvements in Water Tube Steam Generators.
Year: 1898

page_text: Date of Application, 19th Jan., 1898-Accepted, 19th Feb., 1898
COMPLETE SPECIFICATION.
Improvements in Water Tube Steam Generators.
We, SIMPSON, STRICKLAND & COMPANY, LIMITED, and FREDERIC STRICKLAND,
all of Dartmouth, in the County of Devon, Engineers 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:
Our invention relates to water tube steam generators of the well known Thorny-
croft type and the objects of our improvements are to arrange the sinuous water
tubes connecting the upper and lower barrels in such manner that any single
tube can be withdrawn and removed from its place in the group and replaced or
a new one substituted without disturbing any other tube or any part of the boiler
or its casing, and also to provide a better arrangement than heretofore of certain
of the circulating tubes below the funnel for the purpose of ensuring a more
efficient distribution of the heated gases.
In Thornycroft and all other water tube steam generators with which we are
acquainted the sinuous tubes are arranged and fixed respectively into the steam
and water barrels either in staggered lines or so closely together that a tube
cannot be passed through amid the group and hence other tubes have to be
displaced in order to remove one, which is both costly and inconvenient.
Now according to our improvements we arrange all the tubes of each group
likely at any time to require removal in straight transverse lines, and not
staggered or zig-zagged, and with a clear space in the longitudinal direction of
the generator between the outer sides of adjacent transverse groups, such space
being of a sufficiently greater length than the outer diameter of any tube, to
enable any tube to be passed freely therethrough.
Thus every tube is plainly visible on inspection from the firebox and if it is
defective it can be removed with ease and small cost through the said transverse
spaces without disturbing any other part. Also, in generators of the type re-
ferred to we close up near their staggered junctions with the upper barrel and for
a suitable distance in each direction a certain number of the tubes in the space
about and below the funnel so as to provide a close tube wall by which too rapid
escape of gases is prevented and heat is better distributed.
In further description of our invention we have annexed 3 sheets of drawings
illustrating the adaptation of our present improvements to three types of Thorny-
croft water tube steam generators which we will now severally describe. In all
the figures like letters of reference are used to denote like parts.
Referring first to Sheet 1. Fig. 1 is a general cross-section of one form of
generator. Fig. 2 is an enlarged developed plan of part of the lower barrel or water
drum thereof, and Fig. 3 is a similar view of the right side of the upper or steam
and water barrel.
A is the upper, and B the lower barrel. T are downtake tubes connecting
same. TT T3 represent one group composed of 3 sinuous water tubes con-
necting the two said barrels. C is the casing, E the fire grate, D the fire door
and F the funnel or untake.

page_text: Our improvement is best shown in Figs. 2 and 3. It will be seen that each
tube group TT2 T3 is arranged, and the tube ends fixed into the respective
barrels A and B, in a straight line transversely of the generator, and that the
spaces between the tubes T T¹, T2 T2, T3 T3, in the longitudinal direction
of the generator are greater than the outer diameter of the tubes themselves by
an amount sufficient to enable any tube to be freely passed through same in the
transverse direction. If for example in a small generator the tube-holes be "
diameter then the space s should not be less than + or of an inch wide. This
arrangement applies equally to the tube holes and spacings both in the upper and
lower barrels.
Referring to the generator illustrated in Sheet 2. Fig. 4 is a cross-section,
Fig. 5 a longitudinal sectional elevation on line z-z thereof with the downtake
tubes removed. Figs. 6 and 7 are enlarged developed views of part of the lower
and upper barrels respectively.
An examination of the latter figures shows four sinuous water tubes T¹ T² To T
of each group arranged in straight transverse lines and spaced apart in the
longitudinal direction as above described. In this generator there is an outer wing
barrel B¹ connected to the lower barrel B by circulating tubes t. The wing barrel is
also connected to the upper part of the upper barrel by side tubes To To arranged as
closely as may be convenient and fixed at their ends respectively into the two barrels A
and B in staggered lines. According to our improvement below the funnel F and
for a suitable distance longitudinally thereabouts a certain number of these tubes in
the line marked T5 in Fig. 4 are raised up at about the point marked P as shown
at to the level of the line Te so as to form below the funnel a close wall as seen
well in Fig. 5 whereby the gases are baffled and prevented escaping direct to and
at the funnel and diverted so as to better distribute their heat over the heating
surface of the generator.
Referring lastly to Sheet 3. Fig. 9 is to the left a front elevation and to the
right a cross-section of another form of generator. Fig. 10 is a sectional elevation.
Fig. 11 is an enlarged development of part of one side of the upper barrel. Fig. 12
is a development of part of one half of the lower central barrel and Fig. 13 a
similar view of one of the wing barrels. This illustrates the adaptation of our
improvement to a generator having an upper barrel A, a central lower barrel B
connected by two sets of sinuous tubes in transverse groups of four, T T2 T3 T¼,
and by downtakes T, and also a pair of wing barrels B₁ B₁ connected to B by cir-
culating tubest and to A by tubes T5 T6 arranged as closely as may be convenient
and staggered at their ends as above described and shown in Figs. 9, 11 and 13.
The groups T T T T are all arranged in transverse lines as illustrated and
spaced in the longitudinal direction of the generator with intermediate spaces s s s
as and for the purpose above explained, and with this type also the tubes T5 T
may be arranged below the funnel as above described.
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that what
we claim is:-
1. In water tube steam generators of the type referred to arranging the several
groups of sinuous water tubes connecting the upper and lower barrels A and B
and fixing their ends thereinto in straight lines transversely of the generator,
the spaces between such lines in the longitudinal direction of the generator being
greater than the outer diameter of the tubes and such that any tube can be
passed freely therethrough between the adjacent tubes in transverse direction
without disturbing any other tube or part of the generator, as herein described
and illustrated in the drawings.
2. In water tube steam generators of the type described in reference to
Sheets 2 and 3 of the drawings, arranging the upper parts of certain of the
circulating tubes T5 T6 at and about the space beneath the funnel substantially

page_text: in the manner and for the purpose herein described and illustrated in Sheet 2
of the drawings.
For the Applicants,
J. C. CHAPMAN,
Chartered Patent Agent, 70, Chancery Lane, London, W.C.,