IMPROVE- MENTS IN STEAM BOILERS AND FURNACES
Year: 1858

page_text: LETTERS PATENT to Robert Armstrong, of North Woolwich, in the
County of Essex, Consulting Engineer, for the Invention of "IMPROVE-
MENTS IN STEAM BOILERS AND FURNACES."-Partly a communication from
David William Bowman, of Pernambuco, in the Empire of the Brazils,
Engineer.
Sealed the 14th December 1858, and dated the 23rd June 1858.
PROVISIONAL SPECIFICATION left by the said Robert Armstrong at the
Office of the Commissioners of Patents, with his Petition, on the
23rd June 1858.
I, ROBERT ARMSTRONG, of North Woolwich, in the County of Essex, Con-
sulting Engineer, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN STEAM BOILERS AND FURNACES," partly communicated to me
by David William Bowman, of Pernambuco, in the Empire of the Brazils,
Engineer, to be as follows:-
These improvements are principally applicable to what are usually de-
nominated " upright" boilers. The outside shell of the boiler may be
constructed of a cylindrical form, or some shape approaching thereto, having
when standing vertically on its base, all its horizontal sections as nearly circular
as practicable, and the more so the greater the intended pressure the boiler is to
bear. Within the lower end of the boiler is placed the furnace chamber or
fire-box, containing a fire-grate of any suitable form and dimensions for the
kind and quantity of fuel required to be used, being surrounded by a space
containing water between the furnace and the shell, of any annulated or other
convenient shape. I then place through or across this annulated water space.
two or more strong tubular passages opposite to each other in pairs, for the

page_text: supply of fuel on each side of the boiler alternately when required. I also in
like manner place one or more pairs of similar but smaller passages, through
which to supply air into the flame above the fuel for the prevention of smoke,
the air being heated by passing through suitable perforations in the fire-brick
and other linings to the air and fuel passages and fire doors, such air and fuel
passages being formed and arranged so as to give the greatest possible strength
and durability to the boiler and furnace while using very high-pressure steam.
The important part of this Invention now to be described has for its object
an increased production of steam in a given time by a certain quantity of fuel,
and is principally accomplished by means of an improved "upright" furnace
flue, into or through which the flame and hot air ascend in their way towards
the chimney or funnel erected thereon. This furnace flue is to be supplied
with a number of hollow tubes fixed transversely across it, through which the
water of the boiler circulates. The particular shape of these cross tubes,
which is prefered as most conducive to the intended effect, is that of two
equal or nearly equal frustums of similar cones, forming one tube by joining
together at their narrow ends, and they are to be connected by each of their
wide ends to the sides of the flue, through which each end slightly projects
into the surrounding annular water space of the boiler. The position of these
cross tubes vertically is to be at about right angles to the axis of the flue, but
in horizontal plan they may be fixed at various angles to each other, so as
sufficiently to occupy the area of the flue, and thereby intercept the most
effective action and heating effect of the ascending column of flame and hot
air, as well as to give additional strength to the flue itself.
It is also to be observed that the placing the above-described cross water
tubes within the upright fire and smoke flues of steam boilers generally,
when continued above the level of the water, furnishes the simplest means of
increasing the expansive power of the steam by "superheating" and drying,
only taking care that the flue and the tubes are both made of increased
thickness and strength for that particular purpose above the water level.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Robert Armstrong in the Great Seal Patent Office on the
23rd December 1858.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
ARMSTRONG, of North Woolwich, in the County of Essex, Consulting 3
Engineer, send greeting.

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-third day of June, in the year of our Lord
One thousand eight hundred and fifty-eight, in the twenty-second year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Robert Armstrong, Her special licence that I, the said Robert Armstrong,
my executors, administrators, and assigns, or such others as I, the said Robert
Armstrong, 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
BOILERS AND FURNACES," partly communicated to me by David William
Bowman, of Pernambuco, in the Empire of the Brazils, Engineer, upon
the condition (amongst others) that I, the said Robert Armstrong, my
executors or administrators, by an instrument in writing under my, or their,
or one of their hands and seals, should particularly describe and ascertain the
nature of the said Invention, and in what manner the same was to be per-
formed, and cause the same to be filed in the Great Seal Patent Office
within six calendar months next and immediately after the date of the said
Letters Patent.
NOW KNOW YE, that I, the said Robert Armstrong, 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, that is to say:-
My said improvements in steam boilers are more particularly applicable to
those usually denominated "upright" boilers, the outside shells of which are
constructed of a cylindrical form, or some shape approaching thereto, such a
boiler having when standing vertically on its base, all its horizontal sections
circular, or nearly so. Within the lower end of this upright boiler is placed
the furnace, furnace flue, furnace chamber, or fire-box, which may be of any
suitable form and dimensions for containing the kind and quantity of fuel to
be used, but I prefer that the said furnace or fire-box be made, as nearly
as practicable, circular or cylindrical, and surrounded by a space containing
water, of any annulated or other convenient shape between the furnace and
the shell of the boiler. Within the said furnace chamber or fire flue, is placed
the fire-grate, but which may also be sometimes placed entirely below the
bottom of the furnace chamber or fire box, and surrounded by brickwork upon
which the boiler may be erected, or in any other convenient manner. The
boiler is also to be supplied with a smoke-flue, chimney, or funnel, proceeding

page_text: from the top of the fire-box, and passing upwards through the top of the
boiler. Or, the smoke-flue may be made to pass out laterally or horizontally
by one or more openings through the water space in the more usual way, but
the former or vertical passage through the steam chamber is to be preferred,
in order to dry and superheat the steam, a provision being made if required,
by the interposition of a fire-brick shield or otherwise, by which occasional,
unnecessary, or accidental overheating or burning of the lower part of the
funnel may be prevented. Through or across the aforesaid annulated or
of
annular water space, two or more strong tubular connections or passages
suitable forms are to be fixed by riveted flanges or otherwise, to the fire-box
and shell respectively, by which the latter mutually support and strengthen
each other. And in order that these connecting passages should thus act as
tubular stays, it is preferred that they should be fixed opposite to each other
in pairs, so that the greatest uniform strength may be thereby obtained. Two
or more of these tubular passages may also be used as fuel passages, or feeding
mouths, through which to supply fuel to the interior of the furnace, and I
prefer that two opposite and lowermost passages may be so used for the pur-
pose of obtaining uniformity of expansion and contraction, and consequent
greater durability in this part of the boiler; and also in order that the furnace
may be supplied with fuel at each side alternately, for the purpose of attaining
the most economical and perfect combustion of the fuel, and the gases arising
therefrom, or otherwise for the purpose of firing or stoking on both sides
simultaneously, and thereby producing the most rapid generation of steam.
One or more of these fuel passages may also be advantageously occupied
by fire-feeding apparatus, or machinery of any suitable construction to be
used in addition to the ordinary hand firing, when a maximum production of
steam is to be effected with economy.
The next improvement also relates to the furnace and the combustion of the
gasses, when either bitumenous or non-bitumenous coal or coke is used. One
or more pairs of the aforesaid tubular stays or passages, not required for the
supply of fuel, and which may be made smaller than the others, are to be
used as air ducts or passages, through which to supply an excess of atmo-
spheric air to the upper portion of the smoky flame, or the unconsumed
inflamable gasses arising from each fresh supply of fuel, accordingly as bitu-
menous or non-bituinenous fuel is used, thus aerifying and oxygenating
the products of combustion, and thereby causing any hydro-carbon and
carbonic oxide gasses they may contain to be more perfectly burned or con-
sumed. And, in order that such camparitively perfect combustion of the
fuel may be attained without the great diminution of the steam generative

page_text: power, and destructive effect on the material of the boiler, which universally
accompanies the admission of cold air for that purpose, the said air passages
are to be partially filled or lined with perforated fire-bricks, tiles, or other
substances for heating the air which passes through them to the interior of
the furnace. It is also preferred that this projection of the air into the
flame above the fuel should proceed from two opposite air ducts at the same
time, so that the two opposing currents may neutralize and commingle with
each other, and with the flame in the upper part of the furnace, and thereby
be prevented from producing the usual injurious "blow-pipe" action of the
flame against the inside of the fire-box, which is so generally produced in
steam boiler furnaces as frequently constructed, where the supplementary air,
especially cold air, is admitted for the alleged purpose of perfecting the
combustion.
The next and most important part of this Invention has for its object an
increased production of steam from a boiler of given dimensions, as well as
by a given quantity of fuel, and consists in an improved construction of the
interior of the furnace chamber or fire-box. In effecting this improvement
the said fire-box is to be supplied with a number of peculiarly shaped hollow
vessels or retorts, which it is proposed to call generators, to be fixed across
the furnace, and crossing each other from side to side. Within and through
these steam generators, which may be considered as so many small boilers,
the water is permitted to circulate, communicating freely with the surrounding
water space at their ends. The position of the generators vertically may be
generally at or nearly at right angles to the vertical axis of the fire-box, so
as to allow the flame and current of hot air from the fire to strike most advan-
tageously directly against their lower sides. In fire-boxes of small diameter,
the position of these generators in horizontal plan may be at right angles
with each other alternately, but in large furnace chambers the generators may
be alternated in superposition with others at angles of forty-five or sixty, or
any other aliquot number of degrees with the former, so that the transverse
sectional area within the furnace chamber may be sufficiently occupied with
horizontal heating surface for the most perfect practical abstraction of the
heat from the rising column of flame and hot air.
The aforesaid steam generators are to be formed of a convenient shape for
manufacturing by welding, rivetting, brazing, or otherwise most suitable to
the metal of which they are composed, and they are especially to be preferred
to be made with each of their ends considerably widened or coned outwards,
the tapered or conical part commencing at or about the middle of their
length, and they may be made either with or without flanges by which they

page_text: may be attached to the sides of the fire-box, being more particularly recom-
mended to be connected thereto by means of angle iron rings and rivets placed
outside the fire-box, the ends of the generators projecting some little distance
into the water space in the manner fully shown in Figures 1 and 2 of the
Drawing hereunto annexed.
Figure 1 represents a vertical, and Figure 2 a horizontal section of the
furnace chamber of a small boiler made according to my improvements, taken
through the centres of the boiler and its two contained generators, which are
the smallest number that can be advantageously used in any case, and of
which A and B in Figure 1 shew longitudinal and cross sections respectively.
This particular form of generator I denominate the "double taper shape."
Instead of both ends of the said generator forming egual frustums of similar
cones, sometimes one end only may be conical while the other portion is
nearly or quite parallel, forming what, for distinction's sake, I call the "single
taper" or "trumpet-shape." Such a trampet-shaped tube or generator may
sometimes be used within the upper part of a fire-box or in a furnace flue of
small diameter, where the latter passes through the steam chamber, when used
for the purpose of superheating and drying the steam where it may not be
be required to act as a stay. But in the middle of the fire-box itself the
double taper-shaped generators are prefered to be exclusively used, for their
greater strength and superior steam-generating qualities, and also because,
when crossed at right angles, the greatest number can be got into a given
height of boiler, or the same collective area of steam generating surfaces can
be brought nearer to the fire.
The mode of fixing the aforesaid steam generators to the fire-box by means
of angle-iron rings, either riveted or otherwise, by which they are made to
project into the water space and thereby enabled to carry the escaping steam
from the ends of the generators away from the vertical sides of the fire-box,
consequently preventing any injurious repulsion therefrom, is also equally
applicable and advantageous to single taper-shaped as well as parallel tubes,
when such tubes are placed horizontally in the fire-boxes or furnace chambers
of boilers, and as such I claim it to be my Invention. I lay no claim to the sole
right of making or using single-tapered or trumpet-shaped tubes themselves,
but only this mode of fixing either single-taper, double-taper, parallel, or any
other shape of tube or generator, when the same is fixed horizontally across
the fire-box, furnace flue, smoke flue, pipe, funnel, or chimney of any kind of
steam boiler whatever, such mode of fixing being substantially set forth in
elevation, sections, and plan, @ B, C, C, and D, respectively in Figures 1 and
2 in the aforesaid Drawing. Although the said Drawing represents the fire-

page_text: box as containing only two generators, it must be distinctly understood that
any other convenient number may be used according to the size of the fire-box,
and generally not less than three or four are to be prefered, two only being
shewn in the Drawing for the purpose of rendering the mode of fixing more
clearly seen and described. The enlargement of the ends of the generators is
also preferred to be greater in proportion as the number of generators
is less, in order to give greater support and stiffness to the sides of the
fire-box.
Claim 1st. Firstly, I claim as my Invention the particular form, con-
figuration, and general arrangement and mode of fixing the peculiar shaped
water retorts, water tubes, or steam generators, as herein-before described
and denominated the "double taper"-shaped generators," and whether such
generators are placed horizontally or in any other position, although the
horizontal position is to be prefered. I do not claim any particular degree of
taper or proportion between the length and the greatest or least diameters of
the conical portions of the generators, but prefer that the degree of taper or
widening out of the ends of each generator may be such, that when any given
number of generators are placed horizontally across the fire-box of an upright
boiler, the horizontal intercepting areas of heating surfaces of all the generators
together may be such as will, at least, be equal to the cross sectional area of
the fire-box itself, so that the flame in its passage upwards from the fire may
be sufficiently intercepted by successive steam generating surfaces, and
by which the heat will be effectually extricated and imbibed by those
surfaces.
Claim 2d. Secondly, I claim the mode of fixing with angle-iron rings in
the water space, and the extension into the water space, of any kind of tube,
pipe, generator, or hollow parrallel stay, containing water, when placed
horizontally across any kind of furnace chamber, flue, or chimney, connected
with any kind of steam boiler, as herein-before described.
In witness whereof, I, the said Robert Armstrong, bave hereunto set
my hand and seal, this Twenty-third day of December, in the year of
our Lord One thousand eight hundred and fifty-eight.
ROBERT ARMSTRONG. (L.S.)