IMPROVEMENTS IN STEAM BOILER AND OTHER FURNACES
Year: 1869

page_text: LETTERS PATENT to Alfred de Pindray, of 13, Boulevart St. Martin,
Paris, in the French Empire, Civil Engineer, for the Invention of
"IMPROVEMENTS IN STEAM BOILER AND OTHER FURNACES."
Scaled the 7th September 1869, and dated the 18th March 1869.
PROVISIONAL SPECIFICATION left by the said Alfred de Piudray at
the Office of the Commissioners of Patents, with his Petition, on
the 18th March 1869.
I, ALFRED DE PINDRAY, of 13, Boulevart St. Martin, Paris, in the
French Empire, Civil Engineer, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN STEAM BOILER AND OTHER FURNACES," to
be as follows:-
This Invention relates to improvements in the construction of furnaces
of steam boilers by which an entire consumption of the smoke is
obtained. I construct the furnace of fire-bricks, its axis being in a
vertical plane passing through the centre of the boiler. The furnace has
vertical sides and its width is equal to rather more than the distance
between the centres of the water-heating tubes which are placed below
the boiler. The brickwork is carried up vertically to within a few inches of

page_text: the bottom of the heating tubes, from which point it follows the curve of
the said tubes to a certain extent, leaving a free space between them. Where
boilers are not provided with heating tubes I make the furnace chamber
of the same diameter as the boiler. The furnace bridge extends up to
within a few inches of the heating tubes (where such are used) in order
to utilize the heat obtained by radiation. The ash-pit is curved at back
up to the furnace bars so as to prevent any eddies of air and increasing
the draught at least fifty per cent. The fire-bars are placed in an
inclined position in the furnace, dipping towards the bridge. These bars
are made in one piece, and of a depth at the centre of from twelve to
eighteen inches. I make the bearings for the lower ends of the fire-
bars aid in the combustion and smoke consumption by assisting the
draught in the furnace, and also preventing damage to said bearings by
heat. For this purpose I introduce air through the bearing at the end
of the fire-bars, which air being sufficiently heated becomes deoxidized
on coming in contact with the boiler. This improvement is applicable
to the fire-grates of all kinds of furnaces. The opening or openings in
the bearing for the admission of air varies in dimensions according to
the kind of fuel used and the width of the grate. This opening is
further curved in a similar manner to the ash-pit for increasing the
draught. Each time it is wished to examine the fire the damper should
be opened about half an inch only, and when charging with fuel the
incandescent fire is first pushed towards the back of the grate and then
equalized in thickness and an equal proportion of green fuel added. The
furnace doors should then be closed and the damper partially opened a
minute afterwards, and in three minutes it should be opened wide, when
the ash-pit will present a bright appearance.
With a furnace arranged as before described I, 1st, obtain perfect
combustion, prevent the formation of smoke, and economize fuel, thic
air being supplied in a suitable volume, rate, and temperature, the air
passing through the bearing of the fire-bars adding its effect to that
passing through the bars; 2ndly, the carbon is transformed into carbonic
acid, and the gases in passing through the flues give up the whole of
their caloric, and reach the chimney in a cool and almost colorless
condition.
By applying the improvements to what is known as the Belleville
boiler I obtain an entire consumption of smoke. For this purpose I
place an arch above the furnace bars, so as to cause the flames to pass in

page_text: a horizontal direction for the purpose of consuming the smoke before it
reaches the flues in which the gases give up their caloric. I also make
the ash-pit open so as to admit a large amount of air. The back of the
ash-pit is curved, as before described, and tho grato is narrowed con-
siderably, but made of greater length for ensuring a good combustion.
The fire-bars are arranged the same as before, as also the bearing for the
The arch placed above the fire-bars is independent of the flame
deflectors, and prevents the gases reaching the tubes before the smoke
is consumed.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Alfred de Pindray in the Great Scal Patent
Office on the 15th September 1869.
TO. ALL TO WHOM THESE PRESENTS SHALL COME, I, ALFRED
DE PINDRAY, of 13, Boulevart St. Martin, Paris, in the French Empire,
Civil Engineer, send greeting.
-
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eighteenth day of March, in the year
of our Lord One thousand eight hundred and sixty-nine, in the thirty-
second year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Alfred de Pindray, Her special
licence that I, the said Alfred do Pindray, my cxccutors, adminis-
trators, and assigns, or such others as I, the said Alfred de Pindray,
my executors, administrators, and assigns, should at any time agree with,
and no others, from time to time and at all times thereafter during the
term therein expressed, should and lawfully might make, use, exercise,
and vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
STEAM BOILER AND OTHER FURNACES," upon the condition (amongst others)
that I, the said Alfred de Pindray, my executors or administrators, by
an instrument in writing under my, or their, or one of their hands
and scals, should particularly describe and ascertain the nature of the
said Invention, and in what manner the same was to be performed,
and cause the same to be filed in the Great Scal Patent Office within
six calendar months next and immediately after the date of the said
Letters Patent.

page_text: NOW KNOW YE, that I, the said Alfred de Pindray, do hereby
declare the nature of my said Invention, 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 Sheet
of Drawings hereunto annexed, and to the letters and figures marked
thercon (that is to say): :-
My Invention relates to improvements in the construction of the
furnaces of steam boilers, at same time ensuring an entire consumption
of smoke, 1st, by the combination of known elements which are modified
so as to obtain the result desired; 2ndly, by the particular arrangement
of the furnace and boiler and the disposition of the same one with the
other for utilizing the whole of the available heat; 3rdly, by the par-
ticular form and dimensions of the fire-grates, flucs, and other parts
which vary with the horse power and form of the boilers and the fuel
employed.
In describing each part of the furnace I will give the co-efficients
obtained by calculation from given dimensions. I construct the
furnace of refractory bricks, its axis being in a vertical plane passing
through the centre of the boiler. The furnace has vertical sides
and its width equals rather more than the distance between the centres
of two water-heating tubes which are placed below the boiler. The
brickwork is carried up vertically to within about four inches of the
bottom of the heating tubes, from which point it follows the curve of
said tubes to a certain extent, leaving a free space of from two to four
inches all round, even where the tubes are enclosed in brickwork. I
find three inches to be the most suitable space to allow, but this, however,
is determined by the section of the flucs, as will be herein-after seen.
The above space should be in all cases provided. In tubular boilers the
furnaces are of special dimensions, but in other descriptions the furnace
is about six inches less in width than the diameter of the boiler. The
furnace bridge extends up to within about four inches of the heating
tubes (where such are used) in order to utilize the heat radiated, and this
improvement is applicable to the furnaces of all kinds of steam boilers.
The ash-pit is curved at back up to the furnace bars to prevent any
accumulation of air, thereby increasing the draught at least fifty per cent.
In order to determine the dimensions of the furnace I, first, divide by
four feet four inches the heating surface in order to obtain the number
of horse power, and multiply it by twelve inches and ths and divide

page_text: by 10 to obtain the grate surface. The power of the generator may be
increased from 10 to 100 per cent. above its nominal power above
found. 1st, in order to increase the power from 10 to 20 per cent. I
add an extra 10 to 20 per cent. to the horse power and multiply by
twelve inches instead of by twelve inches and ths; 2ndly, to increase
it from 35 to 40 per cent. I multiply by 11 inches and ths; 3rdly,
to increase it from 45 to 65 per cent. I multiply by 11 inches and th;
4thly, to increase it from 70 to 100 per cent. I multiply by 10 inches
and ths. This gives the same result as if the additional 10, 20, 30, 40,
60, 80, 90, or 100 per cent. were already had. For example, in order to
double the power of a twenty horse boiler I multiply forty horse power
by 10 inches and ths and take one-tenth, which gives the grate
surface. By dividing this surface by the width the length of tho
furnace is obtained, to which six inches is added for the ribs and ends
of the bars, and ten inches and ths for the front plate. I allow only
five feet of grate surface per horse power in consequence of my
improved mode of utilizing the heat and the perfect combustion ensured
at the bottom of the fire. The fire-bars are placed in an inclined
position near the base of the fire-bridge, as shown in the Drawings.
For a furnace of sixteen inches in length their inclination would be
about five inches; for a furnace of from 18 to 36 inches they would be
inclined 6 inches; if from 5 feet to 8 feet, eight inches; over eight fect,
ten inches, and so on. In front the fire-grate is about 14 inches from the
bottom of the boiler. The bars are made throughout of a single piece;
at their centre the bars are from 16 to 22 inches below the boiler. The
depth of the fire-bars varies according to the rate of combustion desired,
and the nature of the draught from 5 to 9 inches. The space between
the bars depends on the size and quality of the fuel. For fine quality
fuel the intervals would be about of an inch, increasing to an inch
for large fuel. These dimensions would be slightly increased when
inflammable coal is used, and reduced in the case of poorer qualities.
I make the bearing for the lower ends of the fire-bars an aid to com-
bustion and smoke consumption by assisting the draught in the furnace
and at same time to prevent damage thereto by heat. For this
purpose I introduce air through the bearing at the end of the fire-bars,
which air being sufficiently heated becomes disoxidized on coming in
contact with the boiler. This improvement is applicable to the fire-
grates of all kinds of furnaces. This bearing is embedded in the
brickwork from 4 to 16 inches. The opening or openings in the bearing

page_text: for the admission of air varies in dimensions from an inch to 3 inches
according to the kind of fuel used and the width of the grate. The
opening is further curved in a similar manner to the ash-pit for
increasing the draught. Each time it is wished to examine the fire the
damper should be opened only about half an inch, and when charging
with fuel the incandescent fire is first equalized in thickness and an
equal proportion of green fuel added. The furnace doors should then
be closed and the damper partially opened a minute afterwards, in three
minutes it should be opened wide, when the ash-pit will present a bright
appearance.
In order to find the size of the flues I add to the section of the grate,-
For a boiler of from 5 to 10 horse power 4 square inclics,
For a boiler of from 10 to 20 horse power S square inches,
For a boiler of from 20 to 50 horse power 12 square inches,
For a boiler of from 60 horse power and over 16 square inches.
These dimensions may however be varied without sensibly affecting the
power.
With a furnace arranged as before described I, 1st, obtain perfect
combustion, prevent the formation of smoke, and economize fuel, the air
being supplied in suitable volume, rate, and temperature, while the air
passing through the bearing of the fire-bars adds its effect to that passing
through the bars; 2ndly, the carbon is transformed into carbonic acid,
which gases pass through the flues, give up the whole of their caloric,
and reach the chimney in a cooled state and almost imperceptible.
In applying the improvements to what is known as the Belleville
boiler I obtain an entire consumption of smoke. For this purpose I
place an arch above the furnace bars so as to cause the flames to pass in
a horizontal direction for the purpose of consuming the smoke before
they reach the flues in which they give up their caloric. I also make
the ash-pit open so as to admit a large amount of air. The back of the
ash-pit is curved as before described, and the grate is narrowed con-
siderably, but made of greater length for ensuring a good combustion.
The fire-bars are arranged the same as before, as also the bearing for the
same. The arch placed above the fire-bars is independent of the flame
deflectors, and prevents the gases reaching the tubes before the smoke is
consumed.
Care should be taken to increase the length of the boiler within
the following limits: 23 as a minimum and :: 25 as a maximum.

page_text: The proportions of the bars, their inclination, and spaces are identical
with those before described. The cast bearing for the fire-bars is also of
the same construction. Above the grate I place a brick arch, which
forces the gases to take a horizontal direction and pass, after their entire
combustion is effected, into the tubes, where they give up their caloric.
This arch is used independently of the flame deflectors for the purpose
of preventing the contact of the gases with the tubes before their
combustion is effected. The flue is made of a size to permit of the
expansion of the gases.
For a boiler of from 5 to 10 horse power the flue would have a
section of
-
-
From 10 to 20 horse power
From 20 to 50 horse power
4 square inches,
S square inches,
12 square inches,
16 square inches,
From 60 and over
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plus the section of the grate. The setting may be of fire-bricks cast or
plate iron.
The improvements consist in the application of the arch for directing
the gases into the tubes after being transformed into carbonic acid,
also in the arrangement of the bars and bearing for same grate and
ash-pit.
I would observe that I make no appreciable increase in the size of
the apparatus, which on the contrary occupies less room. The breadth
remains the same, it is increased from 12 to 20 inches in length, it is
also higher but not so as to render it unsuitable.
5 My Improvements in steam boiler furnaces are illustrated in the
accompanying Drawings, Figure 1 of which shows a transverse section
of the improved furnace applied to a double tube boiler; Figure 2 is a
longitudinal section, and Figure 3 is a plan of the same; Figure 4 shows
a plan elevation and longitudinal section of the bearing of fire-bars;
Figure 5, an elevation, plan, and section of a fire-bar; Figure 6, a
transverse section of the improved furnace applied to an ordinary fluc
boiler;
while Figures 7, 8, and 9 show a plan, longitudinal and trans-
verse sections of the improvements as applied to a Belleville boiler.
The same letters of reference indicate like parts in the several Figures.
5
a, boiler having tubes b, b; c, grate composed of bars resting on bed
plate d; e, fire-bridge on which are carried the supports of tubes b;
f, fire-bars supported on bearing d, and suitably spaced according to the
nature of the fuel.

page_text: Having described the nature of my Invention, and the manner of
performing the same, I declare that what I claim as my Invention to
be protected by the herein-before in part recited Letters Patent is,
constructing steam boiler and other furnaces in the manner herein-before
described and shown in the accompanying Drawings, and for the pur-
poses specified.
In witness whereof, I, the said Alfred de Pindray, have here-
unto set my hand and seal, this Eleventh day of September,
in the year of our Lord One thousand eight hundred and sixty-
ninc.
ALFRED DE PINDRAY. (L.S.)
r
ALFRED DE PINDRAY. (L.S.)