IMPROVEMENTS IN STEAM BOILERS AND THEIR FURNACES
Year: 1874

page_text: LETTERS PATENT to John Millward, of Curzon Chambers, Paradise
Street, Birmingham, in the County of Warwick, for the Invention
of "IMPROVEMENTS IN STEAM BOILERS AND THEIR FURNACES."-A com-
munication from abroad by William H. Richardson, of Cincinnati,
PROVISIONAL SPECIFICATION left by the said John Millward at the
Office of the Commissioners of Patents, with his Petition, on the
22nd April 1874.
I, JOHN MILLWARD, of Curzon Chambers, Paradise Street, Bir-
mingham, in the County of Warwick, do hereby declare the nature of
the said Invention for "IMPROVEMENTS IN STEAM BOLLERS AND THEIR
FURNACES," to be as follows:--
This Invention relates to the construction and working of boilers and
the furnaces thereof, so as to facilitate the circulation of the water and
the separation of steam generated, to effect more complete combustion of
the fuel, and to utilize a large portion of the waste heat that usually
escapes by the chimney.

page_text: For applying the Invention to a vertical cylindrical boiler having an
internal cylindrical fire-box, the upper part of the fire-box is made
conical, and a number of bent tubes are fixed, the one end of each tube
to the cylindrical periphery, and the other end to the conical top of the
fire-box, the tubes being so bent as to make square joints at each end.
By this curvature of the tubes and mode of fixing them no strain is
thrown on the joints by changes of figure due to expansion or con-
traction; also the water circulates freely through those tubes from their
lower mouths upwards, and steam generated in them is readily separated
from the water in issuing from their upper mouths into the spacc
above
the fire-box. Of the tubes so fixed some are made longer than the others,
the longer tubes extending lower down in the fire-box and farther inwards
towards its centre, and the shorter tubes being interspaced with them, so
that the products of combustion in rising up the fire-box are caused to
take a star form, the rays of the star increasing in number upwards.
After leaving the fire-box the products of combustion are led by a pipe
through a box or chamber containing a number of tubes, or through a
number of tubes contained in a box or chamber to an outlet. The air
for maintaining the combustion is forced by a fan or blower to pass
through or round these tubes in a direction opposite to that of the
products of combustion, so as to take up from them a large portion of
their heat. The air thus heated is led to a trunk or pipe encircling the
boiler, from which trunk it issues by several nozzles along with con-
centric jets of steam into the fire-box immediately above the burning
fuel, a portion of the air being supplied by a branch from the trunk to
the ash-pit below the fire-bars. The fire may however be placed on a
solid bottom without bars, and in that case the jets of mingled air and
steam are directed obliquely down upon the fuel. The air supplied for
combustion being in either case forced, the fire and ash-pit doors are
kept closed, being only occasionally opened for feeding fuel and removing a
ash.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Millward in the Great Seal Patent Office on
the 22nd October 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
MILLWARD, of 27, Paradise Street, Birmingham, in the County of
Warwick, Civil Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-second day of April, in the
year of our Lord One thousand eight hundred and seventy-four, in
the thirty-seventh year of Her reign, did, for Herself, Her heirs and
successors, give and grant unto me, the said John Millward, Her
adminis-
special license that I, the said John Millward, my executors,
trators, and assigns, or such others as I, the said John Millward, 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 "Iμ-
PROVEMENTS IN STEAM BOILERS AND THEIR FURNACES," a communication to me
from abroad by William H. Richardson, of Cincinnati, Hamilton County,
State of Ohio, in the United States of America, upon the condition (amongst
others), that I, the said John Millward, 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 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 John Millward, do hereby declare
the nature of the said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement thereof, reference being had to the accompanying
Drawings, and to the figures and letters marked thereon, that is to
say:
This Invention relates to the construction and working of boilers and
the furnaces thereof. so as to facilitate the circulation of the water and

page_text: the separation of stem generated, to effect more complete combustion of
the fuel, and utilize a large portion of the waste heat that usually
escapes by the chimney.
For applying the Invention to a vertical cylindrical boiler having an
internal cylindrical fire-box, the upper part of the fire-box is made
conical, and a number of bent tubes are fixed, the one end of each tube
to the cylindrical periphery, and the other end to the conical top of the
fire-box, the tubes being so bent as to make square joints at each end.
By this curvature of the tubes and mode of fixing them no strain is
thrown on the joints by changes of figure due to expansion or con-
traction; also the water circulates freely through those tubes from their
lower mouths upwards, and steam generated in them is readily separated
from the water in issuing from their upper mouths into the space above
the fire-box. Of the tubes so fixed some are made longer than the
others, the longer tubes extending lower down in the fire-box and farther
inwards towards its centre, and the shorter tubes being interspaced with
them, so that the products of combustion in rising up the fire-box are
caused to take a star form, the rays of the star increasing in number
upwards. After leaving the fire-box the products of combustion are led
by a pipe through a box or chamber containing a number of tubes, or
through a number of tubes contained in a box or chamber to an outlet.
The air for maintaining the combustion is forced by a fan or blower to
pass through or round these tubes in a direction opposite to that of the
products of combustion, so as to take up from them a large portion of
their heat. The air thus heated is led to a trunk or pipe encircling the
boiler, from which trunk it issues by several nozzles along with con-
centric jets of steam into the fire-box immediately above the burning
fuel, a portion of the air being supplied by a branch from the trunk to
the ash-pit below the fire-bars. The fire may however be placed on a
solid bottom without bars, and in that case the jets of mingled air and
steam are directed obliquely down upon the fuel. The air supplied for
combustion being in either case forced, the fire and ash-pit doors are
kept closed, being only occasionally opened for feeding fuel and removing
ash

page_text: now proceed particularly to describe the same, and for that purpose I
shall refer to the several Figures on the Drawings hereunto annexed, the
same letters of reference indicating corresponding parts throughout all
the corresponding Figures.
Figure 1 is a vertical section of a steam boiler and apparatus containing
the greater part of this Invention; Figure 2 is a view in section; shewing
the device for dispensing with grate bars; Figure 3 is a cross section of
the boiler immediately above the annular air chamber; and Figure 4 is
a modification of the construction of the heater.
A and B represent respectively the inner and outer shells of the boiler.
The tubes C are attached at their lower ends to the shell A, and at their
upper ends to the conical crown sheet D. The tubes C are bent at both
ends for the purpose of enabling them to enter the sheets at right angles
thereto, the presence of the conical sheet D necessitating the bending of
the upper ends. By the provision and arrangement of this conical sheet
and bent tubes therefore the right angle joint is not only effected, but
the tubes are in such a form as that expansion and contraction will not
strain the joint at either end. The curvature of the upper ends further-
more so inclines the discharge of water therefrom (in the generation and
liberation of steam) with relation to the natural direction of the escaping
steam that a separation of the steam from the water in these discharges
is effected at a point near the crown sheet D, and the water is prevented
from projecting into the steam space. The tubes are so grouped, as
shewn in Figure 1, that the inner row C at the bottom give wide
openings between them for the flame to enter, which openings are
reduced in width by the spaces between the pipes of the next row, the
openings terminating in a point as it were against the last row, so that
these openings are star-like in cross section to conform to the natural
configuration of flame, and being curved upward and inward so as to
contract in lateral extent, also in conformity to the natural form assumed
by flame in a tube or chamber. It is a well-known fact that flame in
all cases naturally. - assumes a tapering pointed form, star-like in cross
section, near the apex, as seen in the flame of a burning candle, and that
it will not follow the shape of a cylindrical tube for but a short distance,
and in this boiler the spaces between the tubes are arranged to conform
to the natural formation of the flame, rather than be at variance there-

page_text: The tubes C, C¹, C", C¹¹¹, are of different sizes and of different lengths,
and in order that the water may pass through the outer tubes as rapidly
and liberate as much steam in proportion to area as the inner ones, the
tubes are arranged so that the inner ones are the longest and largest,
and from that to the outer ones the length is decreased, and the diameter
correspondingly decreased.
In some cases the grate bars usually employed may be dispensed with,
and a solid bottom E substituted, and the fire fed with the necessary
gases to support combustion by the jets F, which are necessarily inclined
towards the bottom. These jets may be steam surrounded by annular
jets of air, or jets of air alone may be used. It is preferred however
that these jets, whether used with a solid fire-bed E or with grate bars,
as shewn in Figure 1, shall be steam surrounded or united with jets F
of air so highly heated as that it shall superheat the steam, and that
these jets shall concentrate in a common focus, where the heat in con-
sequence will be so intense that the gases arising from the coal will be
fully consumed, and the formation of smoke prevented, the component
parts of the steam and air being in the process separated and utilized.
It will be seen by reference to the Drawings that this furnace depends
for its supply of air entirely upon that communicated through pipe G,
which supplies a forced current of air from a blower or other apparatus
adapted to establish and support a current of air. This current of air
passes through a heater H of such construction that the air will pass in
an opposite direction to the products of combustion which operate to
raise its temperature, substantially as shewn, so that its temperature is
gradually increased, and it leaves the heater at a point where it is
hottest. The products of combustion which operate this heater are
conveyed from the furnace I by pipe J, and after passing through the
heater escape at pipe K, the heat so conveyed (which is generally wasted)
being utilized in the heating of the air, which is forced in by jets F to
support and complete combustion and prevent smoke.

page_text: In Figure 4 it is seen as a modification in place of arranging for the
air to pass around the tubes of the heater, and products of combustion
through the interior thereof, this may be reversed, the air being then
made to pass interiorly and the gases exteriorly. As in this furnace the
5 products of combustion are under pressure, the door of the furnace
should not be opened unnecessarily, and when open the escaping gases
may be made to ascend a vertical flume or flue over the door, which
may be attached to the front of the boiler.
It will be seen that in the operation of the heater H, whether made as
0 in Figure 1 or as shewn in Figure 4, the air in entering strikes against
that part of the apparatus which is least heated; and flows thence
towards the part of the heater which is more highly heated, and in the
opposite direction to the products of combustion.
It is obvious that in the furnace of this steam boiler burning oils may
be used as fuel with great economy as compared with furnaces having
but a natural supply of air and natural draft. This furnace furnished
with the focusing jets F described is also applicable to cupolas, blast
furnaces, glass furnaces, and other analogous use.
Having thus described the nature of this Invention, and in what
manner the same is to be performed, as communicated to me by my
foreign correspondent, I claim,-
First. In combination with the shells A, B, and conical crown sheet D
the tubes C, when curved at both ends to meet the shell A. and crown
sheet D at right angles, substantially in the manner and for the purpose
specified.
Second. The arrangement of tubes C, 'C', 0, C1, in the manner sub-
stantially as described, by which the curvature at the lower ends enables
the tubes to enclose a gradually contracting space for flame, and the
grouping forms star-like spaces for the flame, substantially in the manner
and for the purpose specified.
Third. The arrangement of the tubes C, C¹, C¹¹, C¹¹¹, "of different
lengths, the longest being also largest in diameter, and the shortest the
smallest in diameter, substantially as and for the purpose specified.
Fourth. In combination with the solid fire-bed or bottom E for the
steam boiler the jets F of air or air and steam, substantially in the
manner and for the purpose herein described.

page_text: Fifth. In combination with the steam boiler herein described the
pipe G supplying forced air from a blower or other apparatus, combined
with the air heater H, fuel furnace I, and pipe J, conveying the products
of combustion through the heater H, the parts operating substantially in
the manner and for the purpose specified.
Sixth. In combination with the furnace I the jets F, f, of forced
highly heated air, with or without steam, brought to a focus within
the conflagration chamber, substantially as and for the purpose herein
described.
In witness whereof, I, the said John Millward, have hereunto set
my hand and seal, this Twenty-second day of October, in the year
of our Lord One thousand eight hundred and seventy-four.