IMPROVEMENTS IN STEAM BOILERS, AND IN THE COMBUSTION OF FUEL."
Year: 1855

page_text: LETTERS PATENT to Alexander Chaplin, of Glasgow, in the County of
Lanark, North Britain, Engineer, for the Invention of "IMPROVEMENTS IN
STEAM BOILERS, AND IN THE COMBUSTION OF FUEL."
PROVISIONAL SPECIFICATION left by the said Alexander Chaplin at the
Office of the Commissioners of Patents, with his Petition, on the 10th
April 1855.
I, ALEXANDER CHAPLIN, of Glasgow, in the County of Lanark, North Britain,
Engineer, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN STEAM BOILERS, AND IN THE COMBUSTION OF FUEL," to be as follows,
that is to say:-
This Invention relates more particularly to steam boilers of the vertical
tubular class, the outer shell of the boiler being a vertical cylinder with an
inside fire box in its lower part. From the crown of this fire box a series of
flue tubes pass vertically upwards to a top tube plate, through which the flue
currents pass to a smoke box or draught chamber communicating with the
chimney. The water surrounds the outside of the fire box and the tubes, the
steam passing off by an annular chamber at the top surrounding the smoke

page_text: chamber. The fuel tubes are conical, or tapered with their small ends
upwards, so that whilst under this arrangement the heat acts much more
effectively upon the tube surface than when the tubes are plain cylinders;
the steam can also pass off from the exterior of the tubes more freely. These
tubes are inserted in their tube plates by being passed up through the fire box
crown from below. The wide lower end of each tube has a tapered shoulder
upon it, and the narrow upper end projecting through the smoke box tube
plate has a nut upon it, so that by screwing up this nut the tube is made to
bear well up into its supporting holes in the plates. These tubes also act as
longitudinal stays for the boiler. In removing the tubes they are easily
slackened out by slackening off the top nut, and then tapping the upper end of
the tube with a hamnier. The boiler shell is continued down in its solid form
below the fire bar level, so as to form a close chamber beneath the grate;
combustion of the fuel on the bars is forced or heightened by forcing in atmo-
spheric air from below by a fan or other agent, as a high-pressure steam jet,
for example. The draught current passing off to the chimney is governed by
a valve, so that by closing this valve more or less a greater or less air pressure
may be kept up beneath the grate bars, thus forcing combustion of the fuel
thereon. These arrangements are all applicable to boilers of various forms
under modifications corresponding to the actual class of boiler to be used.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Alexander Chaplin in the Great Seal Patent Office on the
10th October 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
CHAPLIN, of Glasgow, in the County of Lanark, North Britain, Engineer, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Tenth day of April, in the year of our Lord One
thousand eight hundred and fifty-five, in the eighteenth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
Alexander Chaplin, Her special license that I, the said Alexander Chaplin,
my executors, administrators, and assigns, or such others as I, the said
Alexander Chaplin, my executors, administrators, or 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,

page_text: 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 IN THE COMBUSTION OF FUEL," upon the condition (amongst
others) that I, the suid Alexander Chaplin, by an instrument in writing
under my hand and seal, 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 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 Alexander Chaplin, do hereby declare
the nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement in writing, reference being had to the accompanying Drawings, and
to the letters and figures marked thereon, that is to say :-
My said Invention relates more particularly to steam boilers of the vertical
tubular class, the outer shell of the boiler being a vertical cylinder with an
inside fire box in its lower part. From the crown of this fire box a series of
flue tubes pass vertically upwards to a top tube plate, through which the flue
currents pass to a smoko box or draught chamber communicating with the
chimney. The water surrounds the outside of the fire box and the tubes, the
steam passing off by an annular chaniber at the top surrounding the smoke
chamber. The flue tubes are conical, or tapered with their small ends upwards,
so that whilst under this arrangement the heat acts much more effectively
upon the tube surface than when the tubes are plain cylinders; the steam can
also pass off from the exterior of the tubes more freely. These tubes are
inserted in their tube plates by being passed up through the fire box crown
from below. The wide lower end of each tube has a tapered shoulder upon it
and the narrow upper end projecting through the smoke box tube plate has
a nut upon it, so that by screwing up this nut the tube is made to bear well up
into its supporting holes in the plates. These tubes also act as longitudinal
stays for the boiler. In removing the tubes, they are easily slackened out by
slackening off the top nut, and then tapping the upper end of the tube with a
hammer.
Combustion of the fuel on the grate bars is forced or heightened by forcing
in atmospheric air from below by a fan or other agent, as a high-pressure
steam jet, for example. To carry out this forcing system, the boiler shell is
continued down in its solid form below the fire bar level, so as to form a closo
chamber beneath the grate. The draught current passing off to the chimney is
governed by a valve, so that by closing this valve more or less a greater or
less air pressure may be kept up beneath the grate bars, thus forcing combus-

page_text: tion of the fuel thereon. These arrangements are all applicable to boilers of
various forms, under modifications corresponding to the actual class of boiler
to be used.
And in order that my said Invention may be properly understood, I shall
now proceed to describe the several explanatory Figures on the Sheet of
Drawings hereunto attached.
Figure 1 on the Sheet of Drawings is a vertical section of a portable steam
boiler of the upright or vertical class, as constructed according to my Inven-
tion; Figure 2 is a vertical section of a steam boiler of a slightly modified
form; Figure 3 is an elevation of a portable steam boiler with an engine of
the ordinary construction, shewing one mode of carrying out my system of
forced combustion; and Figure 4 is a vertical section, shewing the mode
of working out the same system in the case of large fixed boiler furnaces.
In the boiler represented in Figure 1, the outer shell A is a vertical cylinder,
with a hemispherical top B, and with an inside cylindrical fire box C in its
lower part. From the crown D of this fire box a series of flue tubes E pass
vertically upwards to a top tube plate F, through which the fluc currents pass
into a curved funnel-shaped smoke box or draught chamber G communicating
with the chimney II. The boiler water surrounds the outside of the fire box C
and the tubes E, and the steam passes off from the annular space in the top B
of the boiler, and encircling the smoke box G. The flue tubes E are conical,
or tapered with their small ends upwards, and they are inserted in their tube
plates D and F by being passed up through the fire box crown from below.
The upper ends of the tubes are screwed externally to receive nuts I above the
top plate F, by screwing which nuts the tubes are made to bear well up into
their supporting holes in the plates. The tubes may also be tightened up by
means of the nuts if they become slack after use, and they serve as longitu-
dinal stays for the boiler. When the tubes are to be taken out of the boiler,
the top nuts I are screwed off them, and the tubes, being tapped on their tops
by a hammer, are easily removed through the fire box.
The boiler represented in Figure 2 differs from that represented in Figure 1,
and just described, in as far as regards the shape of the top of the boiler and of
the smoke chamber G above the tubes. The cylindrical portion A of the
boiler (Figure 2) is carried up to the top, and is surmounted by a flat plate J,
whilst the smoke box G is made conical, and larger than in Figure 1, but
still leaving a sufficient steam space between it and the top and sides of
the boiler.
The boiler represented in Figure 3 is the same externally as that represented
in Figure 1, but internally it is of the ordinary construction, as indicated by

page_text: dotted lines. It is represented as having a small steam engine attached to it,
consisting of a steam cylinder K, supported in a vertical position by a pair of
brackets L springing from the top of the boiler. The piston rod issues at the
lower end of the cylinder, and drives a shaft M, carried in bracket bearings N
near the bottom of the boiler.
The boiler delineated in Figure 1 is represented as constructed for carrying
out my system of forced combustion in the fire, and for this purpose the boiler
shell A is continued down in its solid form below the grate bar level, so as to
form a closed chamber or ash-pit O beneath the grate, or the boiler may stand
upon a separate ash-pan, contrived to form a closed chamber. Access is had to
this chamber when necessary by a door, such as is represented at P in Figure 3.
Atmospheric air is forced into this closed chamber O beneath the grate by
means of a small fan Q fixed to the side of the boiler, the discharge pipe R
of the fan passing down the side of the boiler and entering the chamber O.
Any kind of a fan may be used; and where a large fan is used for other
purposes, it will be sufficient to carry a small branch pipe from the discharge
pipe of such fan to the closed chamber O; but in the present instance the fan
which I have represented is of the duplex kind, previously patented by me,
and which I prefer to use, as it requires but a comparatively low rate of revo-
lution. The fan is represented as driven by a belt S from the fly wheel upon
the engine shaft M, the fly wheel being made with a cylindrical rim to receive
the belt. The current of gases from the fire passing off to the chimney H is
governed by a valve or damper T, adjustable by means of a lever U and rod V,
so that by closing this valve more or less, a greater or less air pressure may be
kept up beneath the grate bars, thus forcing the combustion of the fuel
thereon.
In Figure 2 a casing W is shewn as fitted round the lower part of the
chimney H, so as to form an annular space through which the feed water
is passed before it enters the boiler, and is thereby enabled to take up and
utilize some of the heat remaining in the gases passing up the chimney.
When this arrangement is adopted, a second damper should be fitted into the
chimney, as at X, to retain the heated gases as long as possible in the vicinity
of the feed water. And in some cases, instead of fitting up the first damper
as at T, in Figure 1, I arrange a series of conical plugs upon a frame, as at Y,
to act as a damper, the plugs entering the upper ends of the tubes E, and
retarding, or, if necessary, entirely cutting off the escape of the heated gases
from the tubes.
In the boiler represented in Figure 3 the air blast is produced by the
action of a steam jet, which is conveyed by the pipe W into the closed chamber

page_text: or ash-pit O. The steam jet is made to play in the centre of an inlet mouth-
piece, through which the air finds its way into the chamber O. A damper is
applied to the bottom of the chimney H, as indicated by dotted lines, this
damper being adjustable by the lever U and rod V, as in the former example.
In Figure 4 are represented the arrangements necessary for applying my
system of forced combustion to the furnace of a cylindrical boiler A, set in
fixed brickwork flues B. These arrangements consist simply of a door C, by
which the ash-pit D is closed, and a pipe E, by which a supply of atmospheric
air is introduced below the grate bars F, this air being forced in by means of
a fan, or by blowing apparatus of any convenient kind. The air pressure is
maintained in the furnace, and the heated gases are prevented from passing off
too rapidly, and wastefully carrying heat away, by means of a damper placed
in any suitable position in the flues, as, for example, at G, at the foot of
the chimney H; or, instead of the damper, the flue or flues (after leaving the
boiler), or the chimney, or both, may be constructed of comparatively contracted
dimensions, so as to prevent the too rapid egress of the heated gases from the
furnace, this retardation of the current being an essential feature of the Inven-
tion, the object being to delay the escape of the gases whilst any available
heat remains in them, without diminishing the supply of fresh atmospherical
air at the mouth of the furnace. The mouth of the air pipe E is provided
with an adjustable cup-shaped protector and spreader I, which prevents ashes
from falling into the pipe, and which spreads the air current so as to distribute
the supply uniformly over the grate bars. The arrangements for working out
my system of forced combustion will of course vary in the details with the
peculiarities of the several boiler furnaces to which it may be applied, but the
practical engineer, boiler-maker, or furnace-builder will adopt such modifica-
tions in each particular case as may seem best to him.
Having now described and particularly ascertained the nature of my
said Invention, and the manner in which the same is or may be used
or carried into effect, I may observe, in conclusion, that I do not confine or
restrict myself to the precise details or arrangements which I have had
occasion to describe or refer to, as many variations may be made therefrom
without deviating from the principles or main features of my Invention; but
what I consider to be novel and original, and therefore claim as the Invention
secured to me by the herein-before in part recited Letters Patent, is,―
First, the general arrangement and construction of portable steam boilers,
as herein-before described, in reference to Figures 1 and 2 on the Sheet of
Drawings hereunto attached.
Second, the system or mode of constructing steam boilers with tapered

page_text: fluc tubes arranged vertically with their wider ends next the fire, and fixed in
their tube plates by means of nuts screwed upon their smaller ends, as herein-
before described.
Third, the system or mode of developing and utilizing heat in steam boiler
and other furnaces, by forcing in a supply of atmospheric air beneath the fire,
and by retarding the egress of the heated gases by means of a damper or other
suitable contrivance, as herein-before described.
In witness whercof, I, the said Alexander Chaplin, have hereunto set
my hand and seal, this Ninth day of October, One thousand eight
hundred and fifty-five.
ALEXR CHAPLIN. (L.B.)