Improvements in Steam Generators.
Year: 1894

page_text: Date of Application, 3rd Sep!., 1894-Accepted, 15th June, 185
Improvements in Steam Generators.
We, CHARLES ALBERT KNIGHT and GEORGE WILLIAM THODE, both of
21 Bothwell Street, in the City of Glasgow, Engineers, 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 relates to steam generators embodying the salient features of the
Babcock & Wilcox water tube boiler, and it comprises various improvements in
the construction and arrangement of such boilers to better adapt them for marine
purposes.
The invention also relates to hand hole fittings of the kind described in the
Specification of Letters Patent No. 6961 of 1886 and it has for its object whilst
permitting of easy insertion of the clamp through the hand hole or like orifice in a
header or other part of a steam generator or vessel under pressure to ensure a
tight and absolute safe joint under the highest pressures, with a minimum weight
of material.
In the accompanying drawings which illustrate the invention,
Figure 1 is a longitudinal vertical section and Figure 2 a cross section of a
modification of the improved boiler composed of two independent tube sections
connected to a central steam and water drum.
Figure 3 is a longitudinal vertical section and Figure 4 is a sectional end
elevation of a single ended boiler showing particularly the construction of casing
enclosing the furnace or combustion chamber.
Figure 5 is a midship section of a vessel showing a modification in which the
boiler is fired from the rear or lower end of the inclined water tubes and Figure 6 is
a front elevation of this boiler.
Figures 7, 8, 9 and 10 are views of details hereinafter described,
Figure 11 is a vertical section through the front part of a header for a water
tube steam generator showing the improved hand hole fittings applied thereto,
Figure 12 is a front elevation of the same,
Figures 13 and 14 are respectively an elevation and plan of one modification of
the clamp and
Figure 15 an elevation of another modification in the form of a tapered plug
adapted to completely close the hand hole.
Figure 16 is a plan of another modification in which the bolt is secured by a nut
made independently of the cap.
Referring particularly to Figures 1 and 2 the double ended form of boiler
therein represented is composed of two independent sets of inclined water tubes A, A,
connected to separate end headers B, B, at front and rear, the rear headers of both
sections being connected to a steam and water drum or reservoir C placed centrally
over these headers. Each of the sections of the boiler is provided with a fire
grate or furnace D fired through one, two or more fire doors E and the fire
gases after playing around the inclined water tubes A and parting with their
heat pass through an uptake F to the smoke stack or chimney. The side
walls of the combustion chamber are formed by water tubes G preferably
laid at the same inclination as the circulating water tubes A and connecting the
reservoir C with sinuous end headers H having straight outer sides as shown by
Figure 7 in order that the spacing or arrangement of the tubes may facilitate the
efficient construction of the casing I. Access of the heat of the furnace to and

page_text: its radiation through the casing are in great measure prevented by interposing in
the spaces between the water tubes G constituting the side walls and the casing
small air tubes G shewn particularly at Figures 9 and 10. Or in lieu of this
arrangement the side walls may be formed as indicated at Figures 2 and 8 by oval
tubes bearing against each other and having their ends reduced and rounded
where they are expanded into the end headers H.
The steam generator represented at Figures 3 and 4 is single ended and similar
in construction to a single section of that described with reference to Figures 1
and 2.
In each case the inclined water tubes are or may be of larger diameter at
the lower part of the boiler, or immediately over the furnace, than in the upper
part in order to promote the better combustion of the fire gases, and the tubes in
the upper part are grouped more closely together so as to utilize the heat from
the furnace gases passing between them.
Figures 5 and 6 represent a steam generator in which the arrangement of the
furnaces is contrary to that usually adopted for water tube boilers, the boiler front
being situated at the rear and the furnace fired from under the lower end of the
inclined circulating water tubes. This arrangement has the advantage of providing
increased depth of furnace towards the rear wall J from the fire door E as the
volume of gases from the fuel increases. The arrangement of the inclined water
tubes corresponds with that described in the Specification of Letters Patent
No. 3456 of 1893 in being divided into two sections A and A¹ with an interposed
combustion chamber L, but the usual single section arrangement may be used.
The main drum C is situated over the firing end of the boiler and is nearer the
middle of the ship where greater head room is available.
The boilers where two are placed athwartships as indicated at Figure 5 can
be set closer together whilst permitting of drawing out the tubes downwards into
the stoke-hold, and all the mountings and fittings are brought into the firing room
within easier reach of the firemen or engineers.
Referring to the improved hand hole fittings represented at Figures 11 to 16 the
circular haud hole orifice a in the header A. or other part of a boiler or pressure vessel
is tapered, the orifice at the outer side of the plate A being smaller than at the inside
and in it is fitted a correspondingly tapered or conical clamp or plug B the said plug
being reduced at two opposite points of its periphery as indicated at Figures 13
and 14 to permit of its insertion through the hand hole; or as indicated at Figure 15
an entire tapered or conical clamp or plug may be used and entered through a
larger hand hole at any point on the header. The clamp or plug B is fitted into
the tapered hand hole orifice with the screw-threaded bolt and (which in this case
is made integral with the plug) passing through the orifice and it is secured m
piace by means of a cap C which is internally screw-threaded and formed with a
nut C by which means it may be turned to draw up the plug in the hand hole
orifice. Around the outside of the hand hole orifice a recess d is formed wherein
is fitted a ring or washer D of copper or other soft material and the face of the
cap
when screwed up bears hard on this ring to ensure the formation of a tight
joint, or the face of the recess d may be sufficiently milled thus dispensing with a
ring for the formation of a tight joint. Thus when an entire conical plug is used
tight joints are formed both by the cap and clamp and when the plug with
chamfered edges is employed there is still an inside joint with small openings
through which slight leakage only would take place in the event of fracture or
giving way of the screwed cap.
As represented at the lower end of Figures 11 and 12 and in plan at Figure 16 a
conical clamp B may be employed having a square taper opening in the centre
into which a threaded bolt 6' with a correspondingly formed head is fitted to close
the orifice a in the header or other part of a steam generator or pressure vessel;
the taper orifice intended to be closed having a small enlargement at two opposite
points of the periphery of its outer side a¹ in the ordinary manner, a cap Cand
close end nut C' or a combined cap and nut being used to form a tight joint outside
of the orifice.

page_text: 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. A double ended water tube steam generator composed of two sets of steam
generating sections of water tubes inclined towards each other and connected to a
central overhead drum substantially as described with reference to Figures 1 and 2
of the annexed drawings.
2. A water tube steam generator having the side walls of the combustion
chamber formed by water tubes connected integrally with the generator, to headers
of special form, being sinuous on one side and straight on the other; and having
air tubes interposed between said walls and an enclosing casing substantially as
described.
3. In a water tube steam generator the arrangement of the heating surfaces
consisting of tubes of relatively large diameter and wide spacing placed immediately
over the furnace to promote the better combustion of the gases and superposed
tubes of smaller diameter and closely spaced to utilize the heat of the gases,
substantially as described.
4. The construction and arrangement of a water tube steam generator with its
furnace fired from under the rear or lower end of the inclined water tubes
substantially as described with reference to Figures 5 and 6 of the annexed
drawings.
5. In hand hole fittings for steam generators or vessels under pressure the com-
bination of a conical clamp or plug and bolt forming a joint or partial joint inside
the hand hole orifice and a cap and close ended nut or a combined cap and nut
with or without a packing ring forming a tight joint outside said orifice, substantially
as described.
Dated this 1st day of September 1894.
CRUIKSHANK & FAIRWEATHER,
62, St. Vincent Street, Glasgow, Agents.