Improvements in Water Tube Steam Generators.
Year: 1899

page_text: Date of Application, 2nd June, 1899-Accepted, 29th July, 1899
COMPLETE SPECIFICATION,
Improvements in Water Tube Steam Generators.
A communication from abroad by the SOCIÉTÉ ANONYME DU TEMPLE, of Paris,
in the French Republic.
I, Philip MiddlETON JUSTICE, of 55 and 56, Chancery Lane, in the County
of Middlesex, Chartered Patent Agent, 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:-
The object of this invention is to apply to or rather combine with water tube
steam generators (particularly those of the class having two or more collectors
connected by tubes of a small diameter), a feed heating device.
It is known that the amount of heat which, per unit of heating surface is
transmitted by the gases of combustion to the water in the interior of the system
of tubes of a boiler, diminishes in proportion as the difference of temperature
between the gases and the water diminishes.
In the boilers in question owing to the circulation, the water is of the same
temperature in all parts of the tubular system and therefore the elements which
lie nearest to the chimney and are exposed to less heat contribute to the total
production of steam in a much smaller degree than those which are situated in
a hotter part.
In order to better utilize these elements it is proposed to cause them to be
filled and traversed with water which is colder than that of the boiler so as to
increase the difference between the temperature of the water and that of the
gases.
These conditions may be realised in the following manner:
In order to describe the invention, take the case of water tube steam generator,
in which the passage of the gases through the tubular system is horizontal, the
chimney being located at one of the ends of the boiler, and where a set of tubes,
forming an arch, isolates the fire place of the system.
This is the case which is diagrammatically represented in Figs. and 2 of
the drawing accompanying this specification.
In this a portion of the system of tubes, situated at the side, where the hot
gases leave the fire place, in order to enter the system of tubes, and comprising
also the tubes of the inner arch or vault, all over the length of the boiler,
remains the same as in the ordinary arrangement; the circulation of the water
therein remains free, and it is therefore in this part that the steam is generated.
The second part of the tubular system situated on the chimney side and the
importance of which relatively to the first part varies according to the maximum
intensity foreseen for the combustion, is modified in order to serve for the
heating of the feed water.
In the drawing the arrangement is represented in cross section in Fig. 1 and
in longitudinal section in Fig. 2.
A designates the upper collector: B B the two lower collectors is the

page_text: chimney; D are the tubes forming the arch or vault; E is the steam generating
system; the feed heating system; G the front end; H the down tubes in the
rear of the generator.
In Fig. 1 the section is taken in the left hand half of the figure, through the
osteam generating system, and in the right hand half, through the system of
feed heating tubes.
As shewn in these figures, the feed heating system F is formed of a set of
coils which are traversed by the feed water under the influence of the pressure
produced by the feed pump.
These coils may be each formed by a tube turned or bent down upon itself, or
by preference, as indicated in the drawing, by a set of tubes similar to those of
the steam generating portion which may be curved in the same direction, or in
a different direction, for instance straight, so as to permit of the employment
of small flanges thereon.
These tubes are connected to one another, alternately at the top and bottom
by connecting boxes f, which device is represented on an enlarged scale in
Fig. 3 in transverse section, in Fig. 5 in plan, and in Fig. 4 in longitudinal
section.
The last tubes f upon the end are coiled and return over the upper boxes
(Figs. 1 and 2) and terminate at the front of the boiler.
"
All the ends, through which the water enters are connected by a dismountable
joint, to a receptacle K, connected to the pressure pipe L of the feed pump.
All the ends, through which the heated water is discharged, can open into
the upper collector; but it is preferable to connect them to a receptacle M,
whence a pipe N passes the water to the collector.
It is desirable to arrange on the box M a suitable valve (not represented) or
the like, by which the pressure in the coils, and consequently the temperature
can be raised, so that if any vaporisation could take place in the feed heating
system it would be but with difficulty.
The connecting boxes f (Figs. 3, 4 and 5) may be formed in the following
manner-
The tubes are expanded at with a "dudgeon
or expander which is intro-
duced through the inspection openings f³ ³ arranged on top of same.
These openings are conical the smaller base being outside. Their largest
diameter is somewhat smaller than that of the hole of the tube facing the same
and they are stopped by a conical plug f which is introduced through the hole
for the tube, before the latter is fixed in its place, and which plug is tightened
with a bolt f, independent of the plug and adapted to hook into a cavity of
suitable shape provided in the plug, as is represented in Figs. 3, 4 and 5, a
metallic joint being thus provided which is but slightly subject to deterioration.
The connecting boxes f of one and the same range may be independent or
held in one and the same block. In the former case they may be connected by
rods passing through the eyes f6 as shown in Figs. 3, 4 and 5.
It will be seen that each coil in this way is independent of the adjacent ones
and can be removed through the front, if the joints are disconnected which con-
nected same to the receptacles K and M, or to the upper collector, as the case
may be, the arrangement being thus of great convenience for dismounting and
inspecting.
If, at the ends of the coils in the receptacles K and M, closing devices are
arranged, then single units of coils may be dismounted in case of any damage,
without it being necessary to empty the boiler or to draw the fire.
The arrangement above described may also be used for easing the boiler by
replacing beneath the feed heating device, the lower collector B by a small
passage or tube at the point where only the steam generating tubes forming the
arch or vault terminate. This tube or passage may be formed for example as a
sort of gutter cast in one piece with or affixed to the bottom of an extension
plate of the collector B. Inspection openings are provided to afford access to

page_text: the joints of the tubes. This arrangement is represented in Fig. 6 in transverse
section and in Fig. 7 in longitudinal section.
P designates the gutter or channel; P¹ the end of the collector B; P2 the
extension of the plate of the collector B; P³ the inspection holes while D are
the tubes of the arch.
The coils may in certain cases be formed as elements perpendicular to the
axis of the boiler, and they may be separate from one another, as in Figs. 1
and 2 or may be united in groups by means of double connecting boxes, at one
of their ends. When the number of connected coils is even, the return tubes
to the front may be dispensed with.
The application of the system above described is not restricted to boilers, in
which the gases pass horizontally, nor to the particular generator above described,
where the return of the gases in the tubular system is simple; but it also extends
to all water tube steam generators having small tubes with water circulation,
such generators being usually formed by collectors connected by tubes of a
small diameter, providing that one or more rows or sets of tubes freely termi-
nating in the collector, are replaced by feed heating coils, in those parts where
the gases are coldest.
Take by way of example a type of generator having small tubes, in which the
chimney is central and where the gases pass in a vertical direction, or a direc-
tion more or less inclined relatively to the vertical, according to the point of the
grate where the gases arise, as is the case in the generator, represented in
elevation and in plan in the diagram Figs. 8 and 9, and applies to Yarrow,
Thornycroft, Du Temple (of the old system) Blechynden and other boilers.
The tubes of the outer ranges, such as T5 T are probably in contact with the
coldest gases, these therefore may be altered into feed heating coils, as above
described. In addition owing to the draught of the gases to the chimney in the
directions,,,, it is probable that the tubes at the four angles y, y', y², y³
of the boiler will be less heated than those which are situated nearer to the
centre.
Therefore instead of arranging a single coil of y toy, the theoretical
principle of the system may be attained more advantageously by dividing each
range, such as T, into two coils, one passing from y to the tube U, and the other
from 2 to the tube U adjacent to U, the receptacles K and M being placed
upon the two ends or faces, at the front and back of the boiler, or the ends of
the coils being brought over to the front as desired.
In this kind of boiler, where the distribution of the temperature of the gases
is less evident than in the type with a horizontal circulation of the gases, expe-
rience will supply valuable indications as to the position to be given to the
coils; the arrangement just indicated being given only by way of a specimen.
It may be mentioned in conclusion, that the system is evidently independent
of the nature of the fuel employed.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, as communicated
to me by my foreign correspondent, I declare that what I claim is:―
1. A steam generator (of the class having collectors connected by water tubes
of small diameter) provided with feed water heating coils replacing the steam
generating tubes at a certain point or points, the object being to take advantage
of the increase of the difference between the temperature of the gases and
water substantially as and for the purpose described.
2. The arrangement of feed water heating coils in a steam generator of the
class referred to substantially as described as an example and illustrated in
Figs. 1 and 2.
3. The arrangement of feed water heating units substantially as described
and illustrated in Figs. 3, 4 and 5.
4. A lower collector provided with a reduced portion or passage for the recep-

page_text: tion of a few of the steam generating tubes substantially as and for the purpose
described and illustrated in Figs. 6 and 7.
5. The arrangement of feed water heating coils in a steam generator of the
class referred to substantially as described as an example and illustrated in
Figs. 8 and 9.