Improvements in Steam Generators of the Water Tube Type.
Year: 1899

page_text: Date of Application, 13th Oct., 1899-Accepted, 23rd Dec.,
1899
COMPLETE SPECIFICATION.
Improvements in Steam Generators of the Water Tube Type.
I, DAVID CROLL, Director of the Etablissement Fijenoord, Rotterdam, Holland,
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 follow-
ing statement: -
This invention which relates to steam generators of the water tube type has
for its object to provide a generator of improved construction and increased
efficiency suitable especially for marine purposes.
The invention is illustrated by the accompanying drawings, Fig. 1 being a
transverse vertical section, Fig. 2 a part longitudinal section and part elevation,
and Fig. 3a part horizontal section and part plan of one modification of the
improved steam generator. Figs. 4 and 5 are transverse vertical sections of two
other modifications in which only a single upper drum is employed.
The improved steam generator is composed under the modification illustrated
by Figs. 1, 2 and 3, of two horizontal water drums a, b, situated near the lower
end of the furnaces c, d, and connected by vertical or slightly inclined water
tubes, or a series of vertical water tubes e and a series of inclined water tubes f,
each to a steam and water drum g, h, above, the steam spaces and the water spaces
of the upper drums being connected by piping i, j, respectively, and the whole
being suitably encased by a casing . The furnaces c, d, are formed by means
of two sets of highly inclined or practically vertical fire grates k, l, situated on
the outer sides of the vertical tubes e, the arrangement of the fire grates in
relation to the tubes being such that fuel spaces y approximating to a V-shape
are formed.
Access to the fire bars is obtained through doorways m, n, on each side of
the casing. The fuel is fed in through doorways o, p, in the casing above the
top of the inclined grates k, l, and drops into the V-shaped space y already referred
to, formed between the inner side of each grate and the outer row or rows of
each set e of water tubes which in this modification are placed vertically. The
inner row or rows of tubes constituting the main body of tubes f connecting
the drums are preferably inclined slightly to the outer vertical row or rows e
so that deep V-shaped combustion spaces or chambers p¹ are left between the
said outer rows e of water tubes and the main body f of the water tubes at each
side of the boiler. At about the level of the top of the fire grate k, l, a perforated
air tube or tubes of fireclay or other material is or are fitted in each com-
bustion chamber p¹ to supply heated air to effect the complete combustion of
the unconsumed gases which pass through between the tubes enclosing the fuel
between them and the firegrate, and which tubes constitute a species of water
tube fire grate. The flame passes then through the main body of tubes to a
central spacer formed by the main bodies of the tubes, thence round and between
the upper drums g, h, to the uptake s.
Firebrick or other baffle plates may be fitted in spaces between the water tubes
in order to direct the fire gases in a sinuous course against the heating surfaces
on their passage from the furnaces towards the uptake s to the chimney, which

page_text: is fitted centrally between the upper drums g, h. The circulation of the water
between the upper and lower drums will naturally be upwards through the outer
rowse of water tubes and downwards through the inner rows f of tubes which
are less exposed to heat; but when desired down-comers t may be fitted out with
the boiler casing to connect the water spaces of the upper and lower drums.
The bottom of the fuel spaces y may be closed by short fire bars or plates extend-
ing from the lower ends of the fire grates k, l, to the outer rows e of water tubes
at or above the line where they are expanded into the lower drums a, b. Or
inclined brick bridges may be substituted to support the fuel at the bottom
of the furnace, extending from about the points of junction of these tubes with
the lower drums to the sole of the boiler, but so as to leave the bottom of the
furnaces c, d, open to admit of the removal of clinker. The grate bars are at
their lower ends supported preferably on levers 22 pivoted outside the furnaces
and extending beyond the casing so that the bars may thereby be moved slightly
should the fuel have a tendency to cake, but the grate may be stationary. The
entire boiler may be supported on a sole plate or plates fitted to the under sides
of each lower drum.
When the drums are short access for firing and cleaning the furnaces may
be provided only at one end of the boiler, and in general firing and cleaning doors
are provided at both ends, and a central partition wall may divide each furnace.
Under another modification illustrated by Figs. 4 and 5 the steam generator is
formed with two lower drums a, b, and one upper drum u, the drum u being connected
to both lower drums by water tubes either slightly bent as shown at Fig. 4, or
curved as shown at Fig. 5, and arranged as already described to form furnaces c, d;.
and the combustion chamber or the generator may be constructed as a single
boiler having one upper drum and one lower drum, and a single furnace and
combustion chamber constructed as described.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is:-
1. A water tube steam generator composed of a water drum or drums, a steam
and water drum or drums thereover, connecting water tubes, and a furnace or
furnaces having an approximately vertical fire grate or grates so placed outwith
the line of the water tubes as to form between them and the grate or grates a
V-shaped space or spaces for the reception and combustion of the fuel, substan-
tially as described.
2. A water tube steam generator composed of a water drum or drums, a steam
and water drum or drums thereover, connecting water tubes of which a number
may be straight and others bent so as to form between them a combustion chamber
or chambers to which air may be admitted and an external furnace or furnaces
formed between the tubes and a vertical or inclined fire grate or grates adapted
to enclose the fuel, substantially as described.
3. The combination with a water steam generator composed of upper and
lower drums and connecting tubes of a rocking fire grate or grates arranged
vertically outwith said tubes and adapted to enclose a fuel space or spaces external
of the tubes, substantially as described.
WALLACE FAIRWEATHER,
Of the Firm of Cruikshank & Fairweather,
Chartered Patent Agents, 62, Saint Vincent Street, Glasgow,
Agent for the Applicant.