Improvements in Steam Superheaters.
Year: 1894

page_text: Date of Application, 13th July, 1894-Accepted, 18th Aug., 1894
COMPLETE SPECIFICATION.
Improvements in Steam Superheaters.
We, JULES GROUVELLE and HENRI ARQUEMBOURG, trading as "La Société
Jules Grouvelle and Henri Arquembourg," of 71, Rue du Moulin Vert, Paris, in
the Republic of France, Manufacturers, 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 consists of improvements in steam superheaters, such improve-
ments being applicable where the superheaters are heated by furnaces specially
provided for the purpose and also where the superbeaters are heated by the
products of combustion from furnaces not specially provided.
The accompanying drawings illustrate the manner of applying our improvements
to a steam superheater heated by means of a furnace specially provided.
Figure 1 is a vertical section on the line 1-1 (Figure 5) showing a steam
superheater embodying the present invention.
Figure 2 is a corresponding front elevation.
Figure 3 is a vertical section on the line 3-3 (Figure 1).
Figure 4 is a vertical section on the line 4-4 (Figure 5).
Figure 5 is a horizontal section on the line 5-5 (Figure 1).
Figure 6 is a horizontal section on the line 6-6 (Figure 1).
Figure 7 is a longitudinal section on an enlarged scale of a steam collector and
the several special parts which serve to connect the end of one of the superheating
pipes to the collector.
The same letters of reference are used to denote like parts in all the figures;
and the respective courses of the products of combustion emanating from the
furnace, and of the steam to be superheated, are indicated throughout the drawings
by arrows in the case of the products of combustion, by plain arrows, and, in the
case of the steam, by arrows marked with a cross.
As will be seen from the figures of the drawings, the superheating furnace,
provided with the improvements devised by us, comprises a furnace proper A,
having a charging door A', through which the furnace is supplied with fuel, and a
door Ax for enabling the ashes to be removed; such furnace being arranged on
one side of a massive block of masonry forming two compartments separated by a
wall As for the greater part of their height. The products of combustion, after
having traversed the said compartments in the direction indicated by the arrows,
pass off through the flue A' into the chimney. On the front side of the furnace
there are provided four apertures. The two upper apertures are closed by doors A*
and A, which enable the superheater to be inspected; one of the two lower ones
serves for the furnace proper, and the other, closed by a door A°, permits the flues
to be inspected. The superheater, provided with the improvements we have
devised, comprises two steam collectors a a, preferably of cast metal, arranged one
above the other and extending through the two compartments of the furnace, each
collector being provided with a central curved and flanged tube or nozzle a*. Two
series of superheating pipes a¹ a¹, preferably bent, as shown, and arranged in
parallel vertical planes, are connected to the collectors. One of the series has

page_text: fewer bends than the other, and is located within that compartment of the furnace
which is above the furnace proper, while the other series, having a large number of
bends, is placed within the other compartment of the furnace. The two collectors
(of ovoid shape in cross section and having vertical plane surfaces) and the two
series of superheating pipes (each comprising the desired number of bends) are
connected by means of the special joints which we will now describe. Each end of
each of the bent superheating pipes a' is threaded so as to receive. a conical
sleeve a³, both ends of which are tapped with screw-threads, one thread turning to
the left and the other to the right, the joint formed by the connection of the end
of one superheating pipe a' and the sleeve a³ being one formed by the juxtaposition
of a rounded part with another rounded part, as illustrated in Figure 7. One end of
the sleeve as may, in certain cases, and for reasons presently explained, be provided
with a screw-threaded plug at, having a square central aperture. Opposite to the
sleeve a³ there is arranged a closing cap a, the rod or bolt of which passes through
a stirrup or yoke-shaped piece a.. This cap, forming with the collector a joint
which depends on the contact of rounded surfaces, is, like all the others, inserted
into the collector through a corresponding flanged tube a*. The ends of the
superheating pipes are fitted to the collectors in the following manner:-
:-The
closing cap a, having been attached to one end of a length of thin wire, is put, on
one side, into the collector a, so as to afford free access to the apertures on the right
and left, provided in the said collector. The end of the superheating pipe a¹ is
then inserted into the collector through the aperture on the right, and the sleeve a³
introduced through the aperture on the left. The sleeve is then screwed on the
end of the superheating pipe by means of a tool which is screwed home in the front
part of the sleeve. The sleeve a is then tightly fitted in the aperture on the right
side of the collector (similarly to the way in which the tubes are fitted in multi-
tubular boilers), and, when this is done, after removing the tool above referred to,
the plug a' is inserted by a key which fits in the square aperture of the plug.
Then, by means of the above-mentioned wire, the cap a is moved opposite the
opening on the left of the collector a, and secured in the position in which it is
represented in the drawings, for which purpose the yoke a and the nut are used.
It will be readily understood that in order to disconnect either extremity of the
superheating pipe, it is sufficient, in the case of each, to repeat in the inverse order
the operations thus described. Where such disconnection is to take place with a
view to exchanging a damaged superheating pipe for a fresh one, the superheating
pipe which is to be discarded, after having been separated from the two collectors,
may be removed from the furnace owing to its elasticity, which permits it to assume
a shape for enabling it to pass between the collectors.
In Figure 6, in order to avoid unnecessary complication in the drawings, the
yokes and closing cap bolts (represented in dotted lines) have only been shown in
connection with the superheating pipes situated at the ends of each series.
It goes without saying that the series of superheating pipes with the greatest
number of bende, instead of being arranged on one side of the series of-super-
heating pipes with the less number of bends, as is assumed to be the case in
the preceding part of this Specification, may be placed either behind or above the
latter series. It. is also obvious that where the superheater is heated by the
products of combustion emanating from a furnace not constructed for the special
purpose of heating it, the general shape or construction of the said superheater
may, and must, be modified to suit each particular case, i.e., according to the
sectional areas and dimensions of the flues through which the products of com-
bustion flow.
--
We will conclude this Specification by mentioning the following circumstances:-
If, in looking at the drawings, we follow the courses or paths taken by the steam to
be superheated and by the products of combustion, respectively, we readily see
that in the series of superheating pipes with the less number of bends, arranged
above the furnace proper, the steam to be superheated circulates in the same

page_text: direction as the products of combustion, which fulfils a condition regarded by us as
important for the reason that the superheating pipes most exposed, or most liable
to be burnt, are securely sheltered and protected from a serious source of
deterioration, since they are only traversed internally by steam containing a
considerable proportion of water, viz., the water which it carries away with it by
mechanical action on issuing from the boiler, and the condensation water produced
during its passage from the boiler to the superheater. In the series of super-
heating pipes with the greater number of bends, which are least exposed to the
damaging action of the fire, the steam to be superheated circulates, on the contrary,
in a direction opposite to that of the products of combustion. Another condition
to be complied with is that of the equal distribution of the steam among all the
orifices admitting it to the superheating pipes connected to the same collector. To
fulfil this condition and to ensure such equal division, the inlet orifices, at certain
points of the superheater, are reduced in sectional area (in throttle-valve fashion),
by the employment of plugs with square apertures or ports a' or by equivalent
devices. In some cases the same result may be obtained in a more simple manner,
viz., by creating at the inlet orifices an adequate resistance, opposing too rapid a
passage of the steam, by the employment of superheating pipes of an internal
diameter reduced to a minimum in each particular instance. A further condition
may be expressed as follows:-The sum total of the effective sectional areas of
the apertures provided for the passage of steam, from the moment it commences
to be superheated, should be considerably less than the sum total of the sectional
areas effectively opened to the passage of steam on its way to the superheater but
not yet superheated. This last mentioned condition, when it is fulfilled, will
naturally have the effect that the rate of flow of the steam will be greatly increased
during the superheating process, which may be regarded as a most advantageous
result, more particularly from the following points of view:-Greater facility is
afforded for changes of temperature; the internal cleaning of the superheater is
rendered necessary; and incrustations or scales are prevented from adhering.
We wish it to be distinctly understood that we do not confine ourselves to the
precise details given above, inasmuch as such details may vary without departing
from the principle of our invention.
'
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we claim :-
.
1. In steam superheaters, the employment of superheating pipes connected to
steam collectors and arranged in series, their arrangement and distribution being
such that, in the case of those superheating pipes which are least liable to be
burnt, the circulation of the steam to be superheated is in the opposite direction to
the circulation of the products of combustion, and in the case of the superheating
pipes most liable to be burnt the circulation of the steam to be superheated is in
the same direction as the circulation of the products of combustion, substantially
as and for the purposes herein set forth.
2. In steam superheaters, the abrupt reduction of diameter or "throttling" of
the orifices admitting steam to the superheating pipes, or the reduction to a
minimum of the internal diameter of each of the superheating pipes, substantially
as and for the purposes herein set forth.
3. In steam superheaters, the adoption of such a ratio or proportion between the
sum total of the sectional areas available for the passage of steam which has not
been superheated, and the sum total of areas available for the passage of
superheated steam, that the rate of circulation of the steam through the super-
heating pipes is thereby extensively increased, substantially as and for the purposes
herein set forth.
4. In steam superheaters, the employment, for the purpose of connecting the
steam collectors with the ends of the superheating pipes, of closing devices with
stirrup-shaped extensions, and couical sleeves forming joints with the steam

page_text: purposes uerem set fortu.
Dated the 12th day of July 1894.
For the Applicants,
G. G. M. Hardingham,
191, Fleet Street, London, E.C., Chartered Patent Agent.