IMPROVEMENTS IN APPARATUS FOR SUPPLYING FURNACES WITH HOT AIR
Year: 1855

page_text: PROVISIONAL SPECIFICATION left by the said 'Frederick Collier Bakewell
at the Office of the Commissioners of Patents, with his Petition, on the
13th June 1855.
I, FREDERICK COLLIER BAKEWELL, of No. 6, Haverstock Terrace, Hampstead,
in the County of Middlesex, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN APPARATUS FOR SUPPLYING FURNACES WITH HOT AIR," being:
a communication from Calvin Fletcher, of North America, to be as follows:-
The Invention consists in heating air to be supplied to furnaces by the heat
of condensing steam in an apparatus composed of two annular steam chambers
connected together by tubes, through which tubes the steam passes on its
escape from the cylinder of a steam engine. Three or more rows of those
tubes are placed concentrically at short distances apart, leaving a circular space,
in the centre for a rotating vane, the apparatus, being enclosed by an air-tight
cylindrical case made of non-conducting material placed excentrically-to-the-
tubes. The rotation-of-the-vane impels air admitted near its axle against, the

page_text: outer surfaces of the tubes, thereby absorbing the heat and condensing the
steam within them. The air thus heated is conveyed to the closed ash-pit of
the furnace, by this means assisting the combustion of the fuel & the con-
sumption of smoke after aiding the condensation of the steam.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Frederick. Collier Bakewell in the Great Seal Patent Office
on the 11th December 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, FREDERICK
COLLIER BAKEWELL, of No. 6, Haverstock Terrace, Hampstead, in the County
of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Thirteenth day of June, 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 Frederick Collier Bakewell, Her special licence that I, the said Frederick
Collier Bakewell, my executors, administrators; and assigns, or such others as
I, the said Frederick Collier Bakewell, 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 APPARATUS FOR SUPPLYING FURNACES WITH HOT AIR," being a
communication from Calvin Fletcher, of the United States, North America,
upon the condition (amongst others) that I, the said Frederick Collier Bake-
well, 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 Frederick Collier Bakewell, 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:
This Invention consists in heating air to be supplied to furnaces for steam
engines or for other purposes, by forcing the air against tubes through which
the escape steam is passing, thereby effecting a saving of fuel and facilitating

page_text: the consumption of smoke, at the same time that the steam is condensed, and
a-supply of hot water is provided for the boiler. The apparatus as applied to
steam engines is susceptible of application either to high or low pressure.
engines, it being alike distinct and separate both from the engine and
furnace; not forming part of either, yet being connected with the engine by
the conduit for the escape steam, and with the, furnace by the conduit for the
heated air.
;
In describing this Invention, I desire to refer particularly to the. Drawing
which is annexed to and forms part of this Specification. The Drawing com-
prises three Figures, marked Nos. 1, 2, and 3, in each of which like letters of
reference are employed to indicate the same parts of the apparatus.
Figure 1 is a perspective view of the apparatus outside; Figure 2 is a per-,
spective sectional view of the same through the axis of the air shaft; Figure 3
represents the arrangements of the tubes and of the triangular strips, to be
hereafter explained...
The apparatus consists of a series of metallic tubes e, e, e, Figures 2 and 3,
(say, ninety-six,) of about one inch diameter and four feet long, open at both,
ends, and arranged in three or more consecutive and concentric circles; as
shewn in Figure 3, each circle containing an equal number of tubes.
The tubes are so arranged in each circle that the central part of each tube
is placed immediately opposite the centre of the space between the tubes in the
next, circle, on a radial line from the common centre of the several circles,
the tubes that form the first or-inner circle being placed about three-eighths
of an inch apart. The ends of each tube are inserted steam-tight into the
hollow annular steam chambers d, d, of about two feet outside diameter and*
one foot inner diameter, the width of each annular chamber being about six
inches, and its depth about four inches.
These annular chambers thus connected by the series of tubes form together
a hollow cylinder, with a central space within the inner circle of tubes of about
one foot diameter, and extending from the top of the upper to the bottom of
the lower annular chamber. In this central space is placed a rotary fan
P. the
axle of which, a, is fixed in the centre, and runs in a step at the bottom of the
apparatus and turns through a, block at the top. To the upper end of the axle,
which projects above the top of the outer case, is attached the driving pulley b
(Figure 1). The wings of the fan-rotate as near to the inner circle of tubes as
safe clearance will admit...
.
Between the tubes of the outer circle are placed triangular strips of wood
(n, n, Figure 3,) or of other suitable material (a non-conductor of heat being
-preferred). These strips are of the same length as the tubes, and are placed

page_text: parallel to and at about half an inch distance from them. The object of these
triangular pieces is to deflect the air driven by the fan, so as to entirely sur-
round the tubes of the outer circle. The collection of tubes is enclosed by an
air-tight cylindrical casing j,j, made of any suitable non-conducting material,
about eight inches in diameter larger than that of the circle of tubes it encloses.
.This casing is fixed excentric to the circle of tubes, being distant from it about
two inches at the nearest point and six inches at the farthest. Two tubes i; i,"
about six inchies in diameter, are inserted in the casing, one near the top, the
other near the bottom, at that part where the space between the casing and
the circle of tubes is the greatest. The tubes i, i, which form the exit for the
heated air, unite into one of larger diameter o, which conducts it to the ash-pit
of the furnace. The pipes f, f; (Figure 1,) inserted steam-tight into the
upper part of the outer casing, serve to conduct the escape steam into the upper
annular chamber. The central space in which the fan rotates is covered
above and below, having only sufficient opening round the axis for the admis-
sion of external air. A pipe 9 leading from the bottom of the lower annular
chamber d¹ carries off the hot water resulting from the condensation of the
steain in the pipes. The apparatus is united and held together by rods .c, c,.
(Figure 1), passing through flanges on the upper and lower ends of the casing,
and secured by screw nuts.
I wish it to be observed that the size, 'construction, and arrangement of parts
may be varied from those in the foregoing description, according to circum-
stances, so long as the principle involved therein remains substantially the
same; and the position of the apparatus may be altered from vertical to
horizontal if more convenient. The dimensions specified indicate the relative.
proportions of an apparatus that has been successfully applied to a high-
pressure engine of ten horse power.
Having described the various parts of the apparatus, I will proceed to state
more fully the mode of operation.
The escape steam of the engine-entering through the pipes f, f, fills the
upper annular chamber d, and passes into the several tubes connected with
the lower annular chamber d', and any portion that remains uncondensed
passes through the pipe g at the bottom; meanwhile, the rotary fan p, being
set in motion by power from the engine applied to the pulley b, impels the air
which is admitted through the openings at the top and bottom of the axis
against, between, and around the tubes throughout their whole series, whereby
the air is heated by coming in contact with the steam-containing tubes, and the
steam within the tubes being wholly or partially condensed, the resulting water'
is drained off and passes away by the pipe g: When the apparatus is applied

page_text: to a high-pressure engine; the pipe ġ conducts the hot water to the supplying
force pump, the remaining steam passing off into the air; but when applied to
a condensing engine, the pipe g is connected with the usual condenser and air
pump, which thus are relieved from a great part of their duty in maintaining a
vacuum. The air, after being heated by close contact with the steam-conducting
tubes, finds its exit through the pipes i, i, whence it is conducted by the larger
pipe o to the space beneath the grates of the furnace.
The door or doors in front of the furnace for the admission of fuel should be
so constructed as to fit close when shut, and the opening to the ash-pit also,
for clearing out the ashes, should be made to fit close. The chamber of the
furnace being thus closely shut and external air excluded, the hot air con-
ducted through the pipe o is the only source whence the combustion of the fuel
can be supported. By this means a more perfect combustion is obtained, and
the smoke is more effectually consumed.
FREDK COLLIER BAKEWELL. (L.S.)