Improvements in Water Tube Boilers.
Year: 1892

page_text: Date of Application, 5th Dec., 1892-Accepted, 7th Jan., 1893
COMPLETE SPECIFICATION.
[Communicated from abroad by LOUIS MARIE GABRIEL DELAUNAY-BELLEVILLE,
of 40 ter, Rue de Douai, Paris, France, Engineer.]
Improvements in Water Tube Boilers.
I, ERNEST DE PASS, of 78, Fleet Street, in the City of London, Fellow of the
Chartered Institute of Patent Agents, do hereby declare the nature of this inven-
tion and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement, reference being had to the
accompanying drawings and to the letters and figures marked thereon, that is
to say -
This invention has for its object the application, to the sections of steam
generators having inclined water tubes (known as serpentine tubes), of individual
return water tubes acting, for each element or section, taken separately, like the
general arrangement of water return, now applied to most systems of water tube
boilers, acts for the entire generator.
This application, to each element or section, taken individually, of an arrange-
ment which has, as yet, only been applied to the entire boiler, enables the whole, or
a portion of, the water of the upper and intermediate tubes, to be continuously
brought back into the lower tubes of each section, without the water being
compelled to pass through the purifying collector and the ordinary return tube to
be distributed amongst the various sections by means of the feed collector which
connects said sections.
By this new arrangement the following advantages are obtained:
A continuous and almost immediate return is obtained, in the tubes most exposed
to the fire, of the water which is expelled therefrom at each instant by the pressure
due to the formation of steam. The abundant feeding of these tubes is therefore
ensured, as well as the constant presence of water in contact with the walls of the
tubes which are the most exposed to the fire, and all local over-heating is therefore
prevented.
The resistance to the flow in those tubes which cause the water to return in
whole, or in part, is decreased, and the disengagement of steam is thus facilitated.
The circulation is increased in each section by continually restoring, to the
lower part, a portion of the water already arrived at the level.
upper
The purifying collector is relieved of the greater portion of the water that it
receives from the sections; this enables the working to be more perfect, as well as
the size and weight of the boiler and the general return tube, or tubes, to be
reduced.
A large quantity of water can be contained in the sections, as there is no fear of
encumbering the purifying collector with water, a large part of the water being
This increase of volume
returned to the lower tubes without leaving the sections.
of water is very advantageous for forced working, and permits of a larger vaporiza-
tion per hour and per square metre of grate surface being obtained with these
generators.
A better utilization of the fuel is obtained by reason of the greatest circulation
of the water in the lower tubes of the sections.
According to the uses to which the generators are destined, the direct return of
the water from the upper to the lower tubes of the sections may be carried out in
various ways.
For instance, the return may be effected from the upper elbow to the lower
header in this case it is sufficient to discharge from the purifier the greatest
amount of water which it, at present, receives.
Or the return of the water may be effected from any intermediate header to a

page_text: lower one.
In this case, the tubes situated above the header from which the return
starts, completes the vaporization of that portion of the water which, not having
been entirely taken by the return tube, may still be mixed with the steam.
Or the return of the water to the lower header may be effected from several
headers, situated at any height on the section, in order to progressively rid the
upper tubes of their excess water and to thus obtain dry steam at the outlet of the
section, while having a large quantity of water in the tubes directly exposed to
the action of the fire.
Lastly, the communication of each section with the feed collector may be effected
by means of the individual return tube of this section.
These water return tubes may be provided with automatic retaining valves,
situated either at the orifice of the lower header of the section, so as to enable the
return water to enter the said header without being expelled therefrom through
the same way under the action of the pressure due to the rapid vaporization in the
lower tube, or at the orifice of the header, or headers of the rows which are above
the first and from which the return tube, or tubes, start, to permit the water to
enter from these headers into the return tube, but not from the tube into these
headers.
These arrangements may be completed by a reverse arrangement located either
at the front or at the back extremity of the section and permitting the direct
escape of the steam produced by each row of tubes.
And in order that my invention may be more readily understood I will describe
the same fully with reference to the accompanying drawings in which the same
letters indicate similar parts.
Figs. 1 and 2 show the arrangement, on one section, of a direct return tube, the
water returning to the front lower header either from the sixth header (shown in
full lines) or from any other, or even from the outlet elbow of the section (shown
in dotted lines). Fig. 1 is a front view, and Fig. 2 is a partial section on the
line x, x, of Fig. 1.
Figs. 3 and 4 show the same arrangement as that shown by Figs. 1 and 2, but
with the addition of the communication between the direct return tube with the
feed collector; the retaining valves being so disposed that:
(1.) The return water can enter the lower header, but cannot enter the feed
collector.
(2.) The water from the feed collector can enter the return tube, and from this
tube the lower header.
(3.) The water in the tube which is connected to the lower header cannot pass
back into the return tube.
The individual return tube could also be in free communication with the lower feed
collector, in such a manner that the water, so returned, benefits the whole of the
sections instead of benefiting each section considered individually.
Fig. 3 is a front view and Fig. 4 is a partial section on the line y, y, of Fig. 3.
Figs. 5 and 6 show the arrangement with direct return collector, putting all, or
only a portion of, the front headers into communication, and especially putting
several upper headers into communication with the lower header. In this arrange-
ment the lower header may be furnished with a valve allowing inlet, but not
outlet, while the other headers are furnished with valves allowing outlet, but not
inlet of the water.
Fig. 5 is a front view, and Fig. 6 is a partial section on the line 2, 2, of Fig. 5.
In these various figures A represents the feed collector of the boiler, B the
lower front header carrying only one tube. C are the intermediate front headers,
the vaporizing tubes being shown at c. An outlet elbow D puts each of the sections
into communication with a steam drum or collector forming no part of. this
invention.
The direct return tube collector is shown. at E, and. the retaining valves are
shown by the letters e, e¹, e¹¹.
The sections of the boilers constructed according to this invention work as

page_text: follows-Referring to the arrangement more particularly shown by Figs. 1 and 2,
the water carried by the steam into the tubes c, is forced by its speed into the
elbow which puts one of the upper headers (here the sixth) into communication with
the direct return tube E, it descends into the tube E and returns into the lower
header B. The steam carrying with it the water not retained by the return tube,
rises in the upper tubes through which it passes in becoming more or less completely
vaporized to return to the purifying collector.
Experience proving that in the sections shown in the drawings herewith, the
water pressure necessary to ensure the flow of the water and steam from one row to
the next immediately above, is less than the vertical distance between the axes of
these two successive rows, the level of the water which will ensue in the return
tube will generally constitute a sufficient pressure on the lower header to ensure
the entry of the return water into this header and to prevent any contrary action.
Any possibility of this contrary action may be guarded against by the use of the
retaining valve
which prevents the water in the return tube coming back into
the header which it left, should the level of the water rise in said return tube,
especially above this header.
e,
The retaining valve e¹ can also be applied for the same purpose; it opens in a
contrary direction to the movement of the valve e, and is so arranged as to prevent
the water in the lower tube of the section being forced into the direct return tube E
during the action of pressure which results from the disengagement of the steam
formed in this lower tube.
The plug or short tube f, has for its object to protect the outlet of the return
tube from the direct influence of the above mentioned action of pressure.
The fresh feed water which reaches the collector A through the purifier, the
ordinary return tube, and the injector, enters the lower header through the
ordinary feed cone nipple which effects a junction between the lower header and
the collector A.
In the case of the arrangement corresponding to Figs. 3 and 4, the working is
the same there is, moreover, introduction of the fresh feed water from the
collector A to the lower header B through the intervention of the direct return
tube E, the valve el preventing the water from the direct return tube returning into
the feed collector in case the level in the individual return tube should be very
high and considerably higher than the level in the general return tube.
If it be considered expedient according to the nature and mode of working of
the sections, the valve ell may be dispensed with, and this will permit of the
individual return water being distributed between all the sections of the same
generator.
In cases where the arrangement would be applied in the manner shown in
Figs. 5 and 6, the direct return would be effected by means of a collector putting
several upper headers into communication with several lower ones.
In this manner, each upper header frees itself of its excess water, which returns
to the lower headers.
The retaining valves e, e, etc. prevent the direct return water being introduced
afresh into the upper headers, and the retaining valve el prevents the water from
the lower header being forced into the return collector, while permitting the return
water to enter into this header.
Having now particularly described and ascertained the nature of this inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is
1. The application to each of the steam generating elements or sections having
inclined water tubes, known as serpentine tubes, of an individual water return
arranged at any suitable height on the sections, substantially as described and
shown.
2. The application to each of the steam generating elements or sections, having
inclined water tubes known as serpentine tubes, of a tube similar to the preceding

page_text: but connecting one spire of the element or section with the steam drum or collector,
so that the steam already formed at a certain height in the elements or sections
can be carried directly into the collector, substantially as described and shown.
3. My improvements in water tube boilers, substantially as described and shown
by the annexed drawings.
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ERNEST DE PASS.