Improvements in Steam Generators.
Year: 1897

page_text: Date of Application, 9th Mar., 1897
Complete Specification Left, 27th Nov., 1897-Accepted, 1st Jan., 1898
PROVISIONAL SPECIFICATION.
Improvements in Steam Generators.
I, WALTER MACKERSIE SMITH, of 16 Otterburn Terrace, Jesmond, Newcastle-on-
Tyne, in the County of Northumberland, Engineer, do hereby declare the nature of
this invention to be as follows:-
This invention has for object improvements in Steam Generators and consists
of a series of Water-tubes placed in the Fire-box of Boilers of the Locomotive
Type, and connecting the water space at one point with that at another, so as to
obtain increased heating surface and better water circulation.
The water-tubes are preferably curved and may connect points, on the same
side, opposite sides, side and ends, or sides and end with the roof of the Fire-box.
For the purpose of fitting, expanding and examination of the tubes, a movable
door or plug is fixed in the outer shell of the Fire-box, opposite to the ends of
each tube.
I, WALTER MACKERSIE SMITH, of 16 Otterburn Terrace, Jesmond, Newcastle-on-
Tyne, in the County of Northumberland, Engineer, 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 improvements in steam generators of the loco-
motive type. According thereto the fire box of such a steam generator is provided
with water tubes arranged to connect the water space at one point with that at
another so as to obtain increased heating surface and better water circulation.
The water tubes are preferably curved and may connect points on the same side,
opposite sides, sides and rear end, or sides and rear end with the roof of the fire-
box.
For the purpose of fitting, expanding and examining the tubes a movable door
or plug is fixed in the outer shell of the fire-box opposite the ends of each tube.
In the accompanying illustrative drawings,
•
Fig. 1 is a longitudinal section on the line of Fig. 2, and Fig. 2 is a trans-
verse section on the line y y of Fig. 1 showing the fire box portion of a steam
generator of the locomotive type with one arrangement of water tubes therein
according to this invention.

page_text: 1 is the outer shell of the firebox, 2 the inner shell of the fire-box and 3 water
tubes arranged within the fire box according to this invention. These tubes, in
the example now being described, are located in vertical planes and extend from
the sides of the inner shell of the fire-box to the opposite top corner of the fire-
box so as to connect the water space between the inner and outer shell with that 5
above the crown of the firebox. They are shown S shaped at one end to allow
for expansion and contraction, and are arranged to cross each other at or near
the centre line of the fire-box, being spaced at suitable distances apart to allow
flame and hot gas to pass around and between them.
I do not confine myself to any particular shape of the tubes, nor do I limit 1
myself to any particular point in the sides or crown of the fire-box at which to
insert the tubes. They may be continued down near to the bottom of the fire
box as shown by dotted lines at 3° in Figure 2; in this case the plate forming the
inner shell 2 may be bulged inward as shown at 2 so as to form projections in
which the lower ends of the tubes 3* can be secured; Or, a suitable junction pipe 1
such as 2b, may be fixed at its ends to the adjacent side of the fire-box and to
it the lower ends of the tubes 3ª can be fixed. The number of tubes shown in
Fig. 1 is thirteen, six being connected to one side of the fire-box and seven to
the other side. The number and also the size of the tubes can however be varied
so as to provide the amount of extra heating surface required.
The ends of the tubes 3 may he securely fixed in place in the inner shell 2, so
as to form steam tight joints therewith, before such inner shell is fixed within
the outside shell; or the tuhes may be so hent that they can be placed in position
by being passed through suitable holes in the inner and outer shells, the ends of
the tubes being suitably fixed in the holes in the inner shell, as for example by:
expanding them by a tube expander inserted from the outside of the fire box
through the holes in the outer shell 1. These latter holes, which may he made larger
than those in the inner shell are provided with suitable removable closures, such
as screw plugs 4, or plates or doors, which admit of ready access being gained to
the tubes for the purpose of examining, cleaning, and removing them, and for
further tightening up their ends in the inner shell 2 when desired.
Figs. 3 and 4 show a fire box with modified arrangements of water tubes accord-
ing to this invention, Fig. 3 being a central longitudinal section on the line cl
of Fig. 4 and Fig. 4 beng a sectional plan on the line zz of Fig. 3.
The water tubes 3 are shown in Fig. 3 as inclined to the horizontal, the angle
being such as to cause free circulation of the water in the tubes and the water
space 5 between the inner and outer shell 1 and 2. The tubes at the upper part
of Fig. 4 are shown as connected to different parts of the same side plate of the
inner firebox shell 2. The tube 3 at the lower part of the said figure is shown
as fixed at one end to one side of the inner fire box shell and at the other end to
the rear end plate 2* of the said inner fire box shell. Fig. 3 shows in dotted
lines the rearward ends of a number of tubes so continued to the end plate 2ª.
The tubes may also be arranged to cross from one side of the firebox to the
other side as indicated in dotted lines at 3ª in Fig. 2. They may also be arranged
to connect the rear end wall 2* to the roof of the fire box as indicated by dotted
lines at 3b in Fig. 1. The points where the ends of the tubes are connected to
the plate or plates forming the inner shell of the fire box, may be arranged
nearer to or further from the longitudinal centre line a¹al or transverse centre
line y y¹ of the fire box, as indicated for example by the pipes 3° shown in dotted
lines in Fig. 4. The shape of the tubes as seen in plan may be variously modified
as indicated in Fig. 4 which shows several different shapes the tubes may assume.
Instead of fixing the ends of the water tubes by expanding them in holes in
the walls and crown of the fire box I sometimes connect them to the fire box by
couplings or unions which enable the tubes to be detached and removed when
necessary through the fire door opening 8 for examination and repair. In this
case the removable closures 4 are dispensed with.
Fig. 5 shows in longitudinal section one form of such a coupling comprising a
hollow screw plug 9 which is screwed tightly into a thickened part of the fire box
2

page_text: shell 2 and projects into the fire box, and a nut 10 which is screwed onto the
inwardly projecting end of the plug and also onto the thickened adjacent end of
the water tube 3. The screwed part of the plug projecting into the fire-box is
made larger in diameter than the screwed part of the tube 3, and the pitch of
the screw thread thereon is also made greater than that in the tube. The two
screw threads on the nut are made the one to fit the plug and the other to fit
the tube. To fix the tube end in place the nut is run back on to the tube which
is placed in position after which the nut 10 is run forward on to the plug and
screwed up tight. As the screw thread on the latter is coarser than that on the
tube end the conical end of the tube is drawn tightly into or against a conical
seat on the plug thus forming a steam tight joint. By screwing back the nut
the tube end can be readily detached. Although I have described and shown the
above coupling as a prefered means of joining the tubes to the fire box, I make no
claim to it herein, as I intend to obtain separate Letters Patent in respect thereof.
I am aware that the tube plate in the fire box of a locomotive boiler has hereto-
fore been connected to the rear end wall 2* of the fire box by rearwardly and
upwardly inclined water tubes upon which the brick arch has sometimes been
placed, also that the said tube plate has been provided with a rearwardly and
upwardly inclined water chamber connected by tubes to the rear end plate 2* of the
fire box, but such constructions, which are outside the scope of my invention, are
objectionable in practice because should anything happen to the boiler tubes 7
(Figs. 1 and 3), the water tubes, or water chamber and tubes prevent ready access
being gained to such tubes. This objection is obviated by arranging the water
tubes in the manner hereinbefore described.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is:-
1. Providing the fire box of a steam generator of the locomotive type with water
tubes the ends of each of which are connected to the same side or to opposite
sides, or to one side and the rear end wall, or to one side and the roof of the fire
box substantially as hereinbefore described for the purposes set forth.
2. A steam generator of the locomotive type having its fire box provided with
water tubes arranged and operating as hereinbefore described with reference to
and shown in the examples represented in Figs. 1 and 2 and in Figs. 3 and 4 of
the drawings annexed and the outer shell of the fire box provided with remov-
able closures for the purpose set forth.
Dated this 27th day of November 1897.