Year: 1886

page_text: [Communicated from abroad by William Sprague Post, of Boston, Machinist,
and Howard De Wolfe Sawyer, of Revere, Engineer, both in Massachusetts,
United States of America.]
I, HENRY HARRIS LAKE of the firm of Haseltine, Lake & Co., Patent Agents,
Southampton Buildings, in the County of Middlesex, do hereby declare the nature
of this 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 relates to steam boilers and to furnaces therefor, and for other
purposes.
The objects of this invention are to provide a boiler which shall utilize the
entire combustible part of the fuel, including the gases liberated during com-
bustion; and also to so arrange the parts of the apparatus and so apply the
intense heat, produced by means of the improved construction, to the water
contained within the structure, as to generate steam with the greatest rapidity
and provide free clearance for it without danger of explosion.
The draught is downward through a water grate on which the fuel rests, (a
depending water leg enforcing this indirect draught,) and the gases are consumed
in the combustion chamber beneath the grate.
The distinguishing peculiarities of the boiler are, the fire-box placed wholly
within the cylindrical boiler shell with water spaces between the two, constituting
water walls; a depending water-leg, the walls of which diverge upwardly at the
rear or inner end of the fire-box, to give clearance to the steam and to enforce a
downward draught; a multiple water grate consisting of two or more distinct
series of water tubes extending from the front water wall to the water leg; and
perforated pipes for supplying jets of fresh air, as described, above and below the
grate, to promote the combustion of the fuel and of the liberated gases.
The novel features of the apparatus are hereinafter described.
In the accompanying drawing:
Figure 1 is a vertical longitudinal section through a boiler embodying the present
improvements.

page_text: A represents the cylindrical shell of the boiler and B the furnace or fire-box placed
wholly within the said shell and held in place by ordinary stay bolts and crown
sheet bars, not shown, and made cylindrical except where flattened at the crown
sheet C, to give sufficient water and steam space above the furnace and the series
of tubular flues D. This form and relative arrangement of the boiler and furnace
constitutes a feature of the invention, and it is advantageous, because these parts,
formed of heavy boiler plate, can thus be made and combined together with
greater cheapness, strength and efficiency than in any other form.
The space within the furnace and above the grate I term the fuel-chamber, and
that below the grate and in part beyond the water leg I designate the combustion
chamber. The inner portion E of this latter chamber is enlarged, to afford
space for the workmen in setting the tubes or making any repairs. To facilitate
this work the front and rear walls of this inner chamber are made vertical and
unobstructed.
F is the body of the water leg and G its oblique foot, both opening into and
communicating freely with the water contained in the hollow water walls H, at
each side of the boiler, and being open at the top to allow free circulation of water
and escape of steam into the steam space. The leg is flanged and rivetted water
and steam tight to the crown sheet Ċ and also to the side walls of the fire-box, as
is the foot G. The upper portion of the water leg is shown strengthened by a
series of stay-bolts I, extending from its front to its rear face, and similar stays
may be provided for the foot if desired.
The water grate is of peculiar construction. It consists of a series of suitable
metallic tubes J extending from the water space in front to the water leg F, and
arranged obliquely in two or more parallel planes, the tubes alternating so that
each tube in the higher range covers the space between two adjacent tubes iu
the range below it, as in Figure 2. This multiple grate, of zig-zag formation,
presents the maximum of grate surface to the fire, gives the grate, as a whole, a
corrugated upper surface to support the fuel, and preserves open spaces for the
downward draught, thus greatly increasing the production of steam, since the
descending flame, between the upper tubes, impinges directly upon those of
the lower series.
A result closely approximating to that secured by this zig-zag arrangement is
attained by placing the tubes of one series directly beneath those of the other
series, since the descending flames pass transversely by the several tubes and
impart their heat to the water flowing through them, thus rapidly converting it
into steam. The caloric current keeps the tubes clean, the downward current,
being necessitated by the depending leg and the draught enters above the grate,
and serving to heat both ranges of tubes to practically the same degree.
The oblique arrangement of the tubes J is desirable to afford clearance for steam
which is or may be formed in them, giving an easy and natural flow of the water
rearwardly and upwardly; but, when the water is admitted under pressure from
the front, the tubes may be placed horizontally.
The tubes J are shown as entering the oblique front of the water leg at a right
angle and extending downwardly from a band or elbow K they are screwed or
swaged into a hollow ledge L forming part of the front water wall and furnished
with a removable front plate M, in order to facilitate any needed repairs-The
bend or elbow in each tube gives to each a limited yield independent of the others,
to provide for unequal expansion by heat; and, in case of leakage, one tube can
be removed and another substituted without disturbing the others. If desired the
leg F and ledge L may be reinforced by an additional thickness of metal along the
line of insertion of the tubes.
The fuel door N, manhole door O and draught door P in the end of the boiler,
may be furnished with thick, flattened iron rings R, to which the end-plates may
be firmly bolted, to secure tight joints and to guard against warping. Within the
draught door P we employ a perforated door or doors Q, as a means of admitting
air jets to the front of the fuel which may be piled against it-Through these

page_text: doors, when desired, the fire may be stirred or withdrawn, the corrugated surface
or zig-zag arrangement of the grate facilitating these operations. Ashes may be
removed or the surface of the foot portion G of the water leg cleared of obstruction
through the manhole or ash door O.
With the present improvements I introduce, through the water space at each
side of the fire-box, one or more air tubes T running from the front rearwardly
about parallel to the grate but somewhat above it; and I extend hollow stay-
bolts S, or short open tubes, from the tubes T through the walls of the fire-box to
admit air in jets to the sides of the fuel. The air, being thus warmed by its
passage in tube T through the hot water, has no tendency to lower the temperature,
but promotes combustion materially.
I also provide a perforated air-pipe U, extending from outside the boiler shell
transversely across the rear end of the fuel chamber and serving to deliver air, in
downward jets, at the inner end of the chamber. A valve or regulating cover to
control the amount of air admitted may be provided. Owing to the downward
draught in the furnace this pipe is subjected to but a moderate heat.
Air jets are also admitted below the grate to assure the perfect combustion of the
inflammable gases; but as the heat is there too intense for an unprotected tube,
I pass air tubes V and W, (either or both) from the outer air through the toe and
beel of the foot G of the water leg, and I provide a series of short hollow bolts Z
opening air passages from such tubes into the combustion chamber, see Figure 1.
The amount of air admitted at these points is also within the control of the
engineer.
I prefer to admit the heated feed water at the top of the boiler, through the
inlet pipe Y, which is provided at its foot with a transverse pipe, perforated to
distribute the water in jets below the water line, see Figure 1.
Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed, as communicated to
me by my foreign correspondents, I declare that what I claim is:—
First. The cylindrical boiler shell A, having fixed within one end of it the fire-
box B of a generally cylindrical form, but flattened at its top as described in
combination with a depending water leg, secured to the top and sides of the fire-
box and with an oblique water grate, substantially as set forth.
Second. The boiler A and fire-box B with water walls H between them, in
combination with an oblique water grate, a depending water-leg, and a series of
stay bolts I extending from front to rear of the water-leg, substantially as set forth.
Third. In a down draught heating apparatus, a depending water leg in combination
with a multiple water grate consisting of two or more distinct series of independent
water tubes among and between which the ignited gases and carbon pass down-
wardly, whereby the heated current comes transversely into contact with the tubes
of the several series successively, for the purpose set forth.
Fourth. The water grate herein described, formed of two distinct series of
parallel metallic tubes arranged in a zig-zag relation to each other, so as to break
joint, and having a free water circulation through them, substantially as set forth.
Fifth.. The described multiple water-grate, consisting of the independent oblique
tubes J, arranged in two or more distinct planes to alternate vertically with each
other and each provided with the bend or elbow K substantially as set forth.
Sixth. The shell A, fire-box B, water walls H and water leg F with its foot G,
in combination with the zig-zag multiple water grate extending obliquely across
the fire-box, with the tubes of its upper series arranged over the spaces between the
tubes of the lower series, substantially as set forth.
Seventh. In a steam boiler or other furnace having water walls on each side and
a downward draught, the depending water leg and a water grate connected thereto
in combination with air tubes extending rearwardly within the water spaces H
and with a series of transverse tubes S opening from the air tubes T into the fire-
pot along the sides of the fuel, substantially as set forth.

page_text: Eighth. In a steam boiler or other furnace, the combination of a water-grate and
depending water-leg separating the fuel chamber from the combustion chamber,
with a perforated air-pipe U, above the grate, serving to introduce currents of
fresh air at the rear of the fuel chamber, substantially as set forth.
Ninth. In a heating apparatus, the combination of a water-grate and depending
water-leg separating the fuel-chamber from the combustion chamber, with one or
more air pipes, VW, introduced laterally through the foot of the water leg below
the grate, and with a series of short hollow bolts Z leading from said pipes into the
combustion chamber, substantially as set forth.
Tenth. The combination of the boiler A, internal fire-box B depending water-
leg F, and zig-zag oblique water grate J, with the perforated door Qand
unperforated door P located at the foot of said grate, substantially as set forth.
of Antahan 1886