Improvements in Steam Boilers.
Year: 1891

page_text: Date of Application, 29th Sept., 1891-Accepted, 16th Jan., 1892
We,
COMPLETE SPECIFICATION.
Improvements in Steam Boilers.
EMILE ARMAND CHARLES, and Gabriel BabilLOT, Engineers, of 26,
and 30, Rue de la Buche, St. Denis, in the Republic of France, 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 and
accompanying drawings that is to say :-
:-
The improved boiler which forms the subject of the present invention preserves
nearly all the advantages of the best known boilers; that is to say, it consists of a
series of separate elements of small capacity; it is tubular, cach separate element
consisting of concentric tubes similar except in dimensions to those ordinarily used ;
it has a cylindrical reservoir, and it is provided with a steam drying device and super-
heater.
The improved boiler is constructed entirely of iron or steel plates, without any
castings but the fittings of the doors of the casing, which may preferably be of
cast steel.
The accompanying drawings are in illustration of the invention.
Figure 1 is partly an end view and partly a vertical section through A B
Figure 3.
Figure 2 is a plan.
Figure 3 a longitudinal section, and
Figure is partly a section through CD Figure 3, and partly a plan with the
covering plates removed.
Figure 5 is a front view.
The boiler consists of a collection of compound tubes divided into vertical sets
of elements, each tube consisting of an outer heating tube, and an inner tube b.
In each set the outer tubes are connected at their ends by tubular rivetted
connections d, and at each end they are closed by small plates sufficiently strong in
which the inner tubes bare fixed so that all the latter are removeable when necessary,
in the same way as the tubes of ordinary boilers.
The lowest tube a of each of the vertical series of these concentric elements
communicates below with a transverse collector e, and above with a similar transverse
collector f, the connection of each series with the collectors being made by means
of copper pipes w.
The upper collector is rivetted to the ends of several water and steam
reservoirs g, h, h, arranged horizontally above the sets of concentric tubes c which
are fixed in an inclined position with a fall of about 13 to 15 centimètres to the
mêtre, to facilitate the disengagement of steam.
The reservoirs g, h, h, also communicate at their other ends with pipes connected
to the pipe, so that when several sets of the apparatus are used in combination
they may be connected in pairs by means of suitable valves.
At the upper part of the central reservoir g and at the middle of its length are
two pipes y connecting it with two drying coils i, j, arranged upon each side between
the reservoir g and h, h, the two coils being afterwards connected to the steam
pipe V which is provided with a safety valve or valves, and a steam stop valve.
Connected with the ends of the reservoirs h, h, and above and below the upper
collector f, are arranged two pipes u, u, connecting the steam and water spaces
respectively with chambers provided with water gauges and with a pressure
gauge.
Or these chambers and gauges may be connected with the central reservoir as
shewn in the drawing, Figure 5.
The reservoirs also communicate by vertical pipes i with the lower collector
e,

page_text: which is provided with feed valves for feeding the boiler with water, and with
a blow-off cock, and moveable covers are provided for cleaning the collectors and
reservoirs.
The whole apparatus is enclosed in a sheet metal case lined with fireclay or other
suitable refractory material.
This case contains an ash pan z, firegrate t, the firebox and smoke_box r, s, and
chimney n. On one of its ends are fitted doors for the ashpan and smoke box,
and at its other end the vertical pipes i, the firebox door E, and soot doors F at
the bottom.
According to the power required, an improved boiler or generator of the kind
described may consist of a single element, and a single reservoir and drying tube,
or more.
By omitting the inner concentric tubes and closing the ends of the outer ones
by covers and making them as well as the reservoirs and case of greater length,
a boiler is obtained resembling the well known types, which is longer and more
cumbrous, but with larger water space, which form may sometimes be usefully
employed and is very cheap.
Finally the upper part of the drying pipes may be supported by T-irons, and a
sheet iron plate is arranged in the smoke box. This plate which forms the back
of the smoke box may be in one or more pieces, and is arranged in front of the sets
of concentric tubes in such manner that the inner tubes can be taken out without
removing the plate, which is fixed by hooked bolts. These bolts pass round the
tubular connections of the outer tubes, their ends then passing through the plates
and being provided with two nuts which fix the plates in position. The entire set
of these plates form together the inner end of the smoke box.
To withdraw a tube, it is only necessary to remove the plate, and take the tube
out in the usual way.
The fire can only therefore communicate with the smoke box by passing first to
the firebox and then back through the inner tubes to the smoke box.
The normal level of the water in the boiler is at about half the height of the
cylindrical reservoirs. The water therefore occupies half the reservoirs, plus the
collectors and the intertubular spaces in the generator. This last is necessarily
very small, consisting only of the annular space between the outer and inner
tubes. The water in the reservoir is kept at the same level as in ordinary boilers.
Although therefore the improved boiler works with a small volume of water, it
is kept at its proper height as easily as if it were very much larger, and the quantity
in the lower part being very small in comparison there is no fear of explosion from
shortness of water.
If it is required to increase the width of the boiler, the sets of concentric
tubes should be arranged in zigzag form as shewn, in Figures 1 and 5, instead of
in horizontal rows.
Often, and especially where forced draught is used, it is advisable to omit the
inner tubes, and to use for the outer ones what are known as serve" tubes, having
8 to 12 thin longitudinal inner ribs. Such tubes may also be used for the inner
tubes, their only objection being their cost.
If ordinary tubes are used, it is preferable to insert thin sheet metal helices in
them (of the kind known as Guébard) by which the flame and heat are retarded as
they pass through the tubes, the efficiency of the generator being thus considerably
increased, whilst the cleaning of the tubes is facilitated as it is only necessary
to withdraw the helices and replace them, which is very easily done through the
smoke box.
The action of the improved boiler is as follows:-It is first filled with water to
the proper height, and the fire being active the flame first ascends between the sets
of inclined concentric tubes below the reservoirs and drying coils, dividing itself
into as many sheets or thicknesses as there are vertical series of concentric tubes.
The outer tubes of these series are therefore directly heated, so that the direct
heating surface may be taken as that of the sum of their surface, provided that they

page_text: are sufficiently far apart to ensure the complete combustion of the gases between
and round them. The gases then pass into the fire box where, if not already
perfect, combustion is completed, and they then pass through the inner tubes to the
smoke box, and thence to the chimney.
The boiler therefore combines large direct heating surface, with effective return
tubes, and shews great efficiency.
The steam formed in contact with the heated surfaces rise to the upper part of
the boiler and fills the reservoirs, taking with it a certain quantity of water which
passes down the vertical pipes to the lower collector where it mixes with the
constantly entering feed water.
There is therefore a continuous circulation, and the water being alternately
heated and then suddenly cooled, the impurities and sediment contained in it are
deposited in the lower collector from which they are expelled by opening the
discharge or blow off cock from time to time.
The reservoirs being in free communication, the pressure will be the same in all
of them and in the drying tubes, and though the steam space may not be large it
is highly heated, and it is well known that for volume may be substituted highly
heated surfaces in the form of heating or drying tubes having a surface of about
Toth of the entire heating surface.
Moreover, however much water the steam may carry on leaving the reservoirs,
it will pass from the drying tubes dry, whilst its degree of dryness can be easily
regulated by the height of the water level in the reservoirs.
By taking the steam from the centre of the boiler (in plan) in marine boilers,
neither the rolling nor the pitching of the vessel will affect its dryness.
It is as easy to keep the water at its proper level in the improved boiler as in
ordinary boilers containing a much larger quantity. The level in the gauge glass
remains steady and without the constant fluctuations found in many multitubular
boilers, but it is advisable that the feed should be as far as possible continuous, by
means of a feed pump working constantly, but the supply froin which can be varied
more or less as required from time to time.
Supposing that a boiler (as shewn in the drawings) has a total heating surface
of 200 square metres, it will weigh about 16000 kilogrammes including the water,
and will occupy a space of about 21 cubic metres. Including the firing room &c.
it will require 15 square metres by 3 metres in height, or 45 cubic metres. At
15 kilogrammes it will furnish regularly 30 kilogrammes of steam an hour per square
metre of heating surface (6000 kilogrammes in all), by the combustion of 900 kilo-
grammes of ordinary coal with a draught of 18 millimetres of water, or about
200 kilogrammes per square metre of grate surface. Its water capacity is
2000 litres.
Supposing the exaggerated estimate of 6 kilogrammes of steam per horse power
at 14 kilogrammes pressure, the total given out would be at least 1000 horse power;
and experience has shewn that this is rather below than above the truth.
With this boiler therefore we have for each horse power
Weight of water
Capacity of water
-
16 kilogrammes.
2 litres.

page_text: Every part of the boiler is easily accessible for all purposes, and it gives all
possible facility for keeping it in condition and for repairing. The slightest defect
is instantly visible and can be at once and easily remedied.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
1. In a boiler, the combination of the separate sets of concentric tubes, the outer
ones connected at their ends by tubular connections, the transverse collectors e
and f, the cylindrical reservoir or reservoirs g, h, h, the heating and drying pipes
or coil, and the descending pipes i, substantially as described and shewn in the
drawings.
2. The separate sets of concentric tubes constituting boilers, and consisting of
outer tubes closed at their ends, and connected together by tubular connections, and
the inner tubes fixed in openings in the ends of the outer tubes, substantially as
described and shewn in the drawings.
3. The separate sets of tubes constituting boilers, and consisting of outer tubes
closed at their ends and connected together by tubular connections, in combination
with the transverse collectors, cylindrical reservoir or reservoirs, heating and drying
pipes or coils, and descending pipes, substantially as described.
4. The improved boiler or steam generator, consisting of the set or sets of
concentric tubes constituting boilers, the transverse collectors, reservoir or reservoirs,
heating and drying pipes or coil, descending pipes, chambers for water and pressure
gauges, plates closing the spaces between the outer tubes in the smoke box, firebox,
and door, smokebox and door, ashpan and door, and outer casing lined with
fireclay or refractory material, all substantially as described and shewn in the
drawings.
Dated this 29th day of Sentember 1901
EDWARDS & Co.,
35, Southampton Buildings, London, Agents for the Applicants.