Improvements in Steam Generators.
Year: 1897

page_text: Date of Application, 6th Apr.,
1897
Complete Specification Left, 4th Feb., 1898-Accepted, 26th Mar.,
1898
Improvements in Steam Generators.
I, OREL DIGHTON ORVIS of No. 3613 North Grand Avenue, in the City of
Saint Louis and State of Missouri, United States of America, Gentleman, do
hereby declare the nature of this invention to be as follows:-
The invention relates to that class of steam generators in which combustion is
maintained upon sets of grate bars consisting of water tubes which are in
communication with the boiler, the draft being downwardly, I mount a boiler
in suitable masonry which comprises the walls of the furnace. A transverse
partition of masonry is built across the furnace so as to form a rear wall for a
pair of fire boxes, this wall being centrally apertured to form a draft flue.
The grate bars are water tubes extending from front to rear of the fire boxes
and having their ends connected with headers which are in turn in communication
with the boiler at its opposite ends.
The two fire boxes are separated by a central flue, and their inner walls are
wholly or in part of metal, and are hollow, and are in communication with the
boiler. These walls are preferably in the form of tubes and extend somewhat
below the grates. The interstices between these tubes may be closed by masonry,
but I prefer to leave at least one of them open for the escape therethrough of a
portion of the products of combustion.
Directly below the central flue between the two fire boxes is located a grate
upon which a fire may be maintained, having an up draft so that the lines of
draft from the three furnaces unite below this central flue. I also use a jointed
scraping bar pivoted at the rearward end of the ash-pit below each of the down-
draft furnaces, and projecting to the forward end thereof and being so disposed that
it will sweep the floor of the ash-pit to throw the cinders accumulated therein
on to the lower grate which is not higher than the floors of these two ash-pits.
Dated this 6th day of April 1897.
I, OREL DIGITTON ORVIS, late of 3613, North Grand Avenue, but now of
Number 3633, Cottage Avenue, City of St. Louis, State of Missouri, United
States of America, Gentleman, do hereby declare the nature of this invention and
[Price 8d.1

page_text: 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 that class of generators in which the down-draft
principle of combustion is employed, and its objects are to increase the efficiency
of such generators by so disposing the circulating pipes that the area of the heating
surface is increased; and to strengthen and render more durable the construction
of the water-tube grates. A further object is to secure an improved means for
precipitating upon a lower up-draft grated surface the cinders falling from the
down-draft furnaces.
These objects are obtained by the arrangement of parts as hereinafter, fully
set forth.
In the accompanying drawings,
Fig. 1 is a front elevation of my improved steam generator;
Fig. 2 is a central longitudinal vertical section on the line 2-2 of Fig. 1;
Fig. 3 is a sectional view, partly in elevation and some of the parts being
broken away, on the line 3-3 of Fig. 2;
Fig. 4 is a detail plan section on the line 4 4 of Fig. 2;
Fig. 5 is a detail transverse vertical section on the line 5-5 of Fig. 2;
Fig. 6 is a transverse vertical section immediately back of and partly through
the furnace front, and a portion of the front being shown in elevation, the invention
being applied to the Lancashire form of steam boiler;
Fig. is a plan section on the line 7-7 of Fig. 6;
Fig. 8 is a vertical section on the line 8-8 of Fig. 6; and
Fig. 9 is a detail of the covering of the fire-box in the form of furnace shown
in Figs. 6, 7 and 8.
The generator is set in masonry as usual. The front wall, A, Figs. 1 & 2
may be of metal, but is preferably of masonry, as shown. The side walls are
represented at A' and the rear wall at A². A transverse partition, a, of masonry
extending from side wall to side wall and from the furnace floor to the crown sheet
of the boiler, separates the fire-boxes, or furnace proper, from the combustion
chamber, and is centrally apertured to form a flue passage. In the construction
represented in Figs. 1 to 5 the ordinary tubular boiler, X, is shown.
The down-draft furnaces are used, and their grate-bars consist of an upper and
lower series of water-tubes designated respectively B, 6 Figs. 2 & 3. The tubes
of the two series are not set staggered as has heretofore been usual, but the tubes
of the lower series, b, are directly below those of the upper series, and interposed
between each pair thus formed is suitable masonry, e¹, whereby weight resting
upon the upper tubes is transmitted in part to the lower set. By this construction
the strength of the grated surface is greatly increased so that it becomes possible
to reduce the thickness of the walls of the tubes without danger of causing them
to sag under the weight of the fuel. By this means the efficiency of the tubes
for the generation of steam is, of course, increased, and furthermore, it becomes
possible to utilize thinner tubing throughout the entire circulating system without
danger from the unequal expansion which would result from the use of tubing
of varying thicknesses. Furthermore, the metal of the tubing, when thin, is
better protected by reason of the more rapid absorption of the heat by the water,
and the life of the tubular grate-bars is thereby prolonged. Another decided
advantage in this construction arises directly from the use of masonry which
tends to store up the heat.
The water-tube grate-bars extend from a rear header, C Fig. 2, to a forward
header, D Figs. 1 & 3, the former being located back of the partition, a, and
preferably well back to the rear end of the boiler, X, and the latter being in-
corporated into and forming a part of the front wall of the generator. These
headers are oblong rectangular chests extending from side wall to side wall,
their thickness from front to rear being their smallest dimension. The rear

page_text: header, C, extends from the floor of the generator to within a short distance of
the crown sheet of the boiler and supports an inverted arch, K, which contracts
the discharge flue from the combustion chamber forward of the header to a com-
paratively small vertical width for purposes hereinafter described, the header
and the arch, K, forming a bridge wall. The tubes, B, b, extend through the
partition, a, but the masonry, e¹, is not continued back of this partition.
The inner side walls of each of the fire-boxes of the down-draft furnaces is
comprised of a series of water-tubes, E, extending from the header, C, to the
header, D, and masonry, e, filling the interspaces between such tubes, and
masonry, a, filling the space between the upper one of the tubes, E, and the crown
sheet of the boiler. Neither the masonry, e, nor el, extends back of the wall, a.
A similar series of tubes, F, extends from the rearward to the forward header
across the upper portion of these fire-boxes. The inner side walls of the fire-
boxes of the two down-draft furnaces are spaced apart so as to form therebetween
the combustion flue, Y, leading to the central aperture in the partition, a, and
I prefer to incline these side walls apart from below upwardly so that the flue, Y,
has a comparatively contracted throat, but incloses a considerable area of the
crown sheet of the boiler, thereby exposing a very considerable surface of the
boiler to the directed action of the burning gases.
An up-draft furnace is located below the down-draft furnaces, as shown at G,
Figs. 2 & 3 and receives the droppings from the down-draft furnaces so as to
insure the complete combustion of the fuel. As it is not desirable to provide an
up-draft furnace having as great width as the combined width of the down-draft
furnaces, I locate it centrally as to the generator, and at each side of it I place
a rotatable cylinder, H, made of any suitable refractory material, such as fire
clay, and mounted upon an axle, h, journaled in the front wall and in the
partition, a, the forward end of the axle projecting beyond the front wall, and
being squared for the convenient application of a crank arm. Any cinders
which may lodge upon the cylinders, H, are precipitated upon the grated sur-
face, G, by their rotation.
Fresh fuel may be fed directly to the up-draft furnace, if desired, feed-doors, y,
Fig. 1 being provided for that purpose. An ash-pit is below the up-draft grates,
and access to it is gained by means of the doors, g¹.
A water-leg, L Fig. 5, leads from the bottom of the boiler, X, at its rearward
end to the lower portion of the header, C, and water-legs, M, M Fig. 3, lead from
the upper portion of the header, D, one at each end, to the upper portion of the
boiler, X. The water tubes, B, b, E, and F, are inclined upwardly from the rear
header so as to promote circulation, and in order that they may be expanded
into the headers, the latter are tilted backwardly so that their faces are per-
pendicular to the tubes. The header, C, is extended below the junction with it
of the tubes, b, so as to serve the purpose of a mud drum, and it is suitably
provided with a blow-off pipe. To prevent the accumulation of steam at the
top of the header, C, vent-pipes, c, are provided leading from the header to
the boiler.
The front header, 1) Fig. 1, is apertured to provide feed openings for the down-
draft furnaces, these openings being provided with doors, each comprising a
frame, O, hinged at its side, as shown at o, so as to swing horizontally, and of a
central panel, P, hinged at its top to the frame, Q, as indicated at 1, p. The
panels, P, are openable for the purpose of providing draft, and swing upwardly
so as to prevent material loss of heat by radiation. Each of the doors is provided
with suitable means, such as a simple form of ratchet, p¹, for supporting the
panel at any desired elevation.
The front wall of the header, 1), is apertured opposite the end of each of the
water tubes entering the header, and also opposite each of the water-legs, M.
These apertures are closed by suitable covers, as shown at B¹, 61, E¹, F¹, and d

page_text: Fig. 1. These hand-hole closures are of a well known type, comprising a plate
within the wall, an arch with-out the wall, and a draw-bar connecting the two
members and carrying a nut upon its outer end,-this form of closure being
preferred as the plates are held in place by pressure from within, and a tight
joint is not dependent upon a strain applied to the draw-bar. To facilitate the
manipulation of the hand-hole covers, certain of the holes may be oblong, and if
desired, may be large enough to provide access to two of the tubes.
In applying the invention to a Lancashire boiler, that is to say, a boiler, Z
Fig. 6, having a greater diameter than the ordinary tubular boiler, and having
large combustion flues, as z, z, the furnace proper is located forward of the boiler
and spaced apart therefrom, as is usual in this type. The headers are vertical
and not tilted as in the generator already described, and consequently the water
tubes connecting the headers are horizontal. In generators of this type, and
if desired in the generator already described, the outer side wall of each of the
down-draft furnaces may also be provided with a series of water tubes, as shown
at F, connecting the two headers. In the Lancashire type the rearward header
forms the back wall of the furnace proper and its covering, or roof, f, is supported
by the water tubes, F, and in this construction the tubes are located not only
across the top of the fire-boxes, but also across the top of the combustion flue, Y.
Two flue openings, Q, Q, are formed through the header, C Fig. 7, and flues,
inclosed by masonry, as shown at g, lead from these flue openings to the flues, z, z,
of the boiler, passing through the front plate, z¹, of the boiler. In this type of
boiler also I find it desirable to provide two water-legs, L, for serving the
header, C, with water from the boiler, one being located near each end of the
header.
The vapors distilled from the three furnaces, that is from the two down-draft
and the one up-draft, meet at the throat of the flue, Y Fig. 6. Those coming
from the down-draft furnaces have lost some of their heat by reason of their
contact with the water tube grate-bars, but their temperature is raised by the hot
vapors ascending from the lower furnace, and they enter the flue, Y, at a kindling
temperature. I leave the space between the lower of the tubes, E, and the inner
of the tubes, B, open so that air passes therethrough into the flue and promotes
the combustion of the gases. By admitting air in this manner, it enters the
flue hot, and hence does not materially reduce the temperature of the burning
gases and thereby check their combustion.
Within the combustion chamber back of the partition, a Fig. 6, the gases are
caused to spread laterally so as to circulate through the interspaces between the
pipes, E, and the pipes, F, by reason of the contracted flue opening over the
bridge wall, whereby the rearward portions of the water tubes render an efficient
surface in the generation of steam. The wide expanse of heating surface pre-
sented to these vapors as they pass backwardly and deflecting them upwardly to
the discharge flue over the bridge wall, and comprising the front wall of the
rear header, C, also robs the vapors of much of their heat, especially
as the header contains the coolest water in the entire system. The
inverted arch of masonry, K, not only subserves the ordinary function of
a bridge wall, but extracts from the vapors considerable of their heat and transmits
it to the water in the header, C.
By drawing the water from the bottom of the rearward end of the boiler, in the
type of generator first described, passing it through a circulating system, all parts
of which are inclined upwardly, and returning it to the front of the boiler and
at a greater elevation than that from which it is taken .therefrom, I am able to
provide for the very rapid circulation of the water, thereby greatly assisting in
accomplishing the desired result of extracting from the vapors of combustion the
largest possible percentage of their heat, and utilizing it in the production of
steam.
5

page_text: Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:-
1. In a steam generator, the combination with a boiler and a pair of down-
draft furnaces spaced apart to form therebetween a flue, and a partition at the
back of the furnaces and having an aperture in register with the said flue, of a
bridge wall back of the partition, water-tubes for the grate-bars of the furnaces
and water tubes forming parts of the adjacent side walls of the fire-boxes of
the furnaces, both sets of such tubes extending backwardly to the bridge-wall, and
service and return connection between such tubes and the boiler.
2. In a steam generator, the combination with a boiler and a pair of down-
draft furnaces spaced apart to form therebetween a flue, and a partition at the
back of the furnaces and having an aperture in register with the said flue, of a
chambered bridge-wall back of the partition, water-tubes for the grate-bars of the
furnaces and water-tubes forming parts of the adjacent side walls of the fire-boxes
of the furnaces, both sets of such tubes extending backwardly to the bridge-
wall and being in connection with the chamber thereof, a water-leg leading from
the boiler to the chamber of the bridge-wall, and return connection between the
forward end of the tubes and the boiler.
3. In a steam generator, the combination with a boiler and the settings therefor
including side walls and a transverse centrally apertured partition, of a header
back of the partition and constituting a bridge-wall, a header forming a part
of the furnace front, two sets of water-tubes connecting the headers and con-
stituting grate-bars for a pair of down-draft fire-boxes, two sets of water-tubes
connecting the headers and arranged in series leading from the plane of the grates
towards the boiler and forming parts of the inner walls of the fire-boxes, such
walls being spaced apart to form a flue registering with the aperture of the
partition, and connection between the headers and the boiler.
4. In a steam generator, the combination with a boiler and the settings therefor
including side walls and a transverse centrally apertured partition, of a header
back of the partition and constituting a bridge wall, a header forming a part
of the furnace front, two sets of water-tubes connecting the headers and con-
stituting grate-bars for a pair of down-draft fire-boxes, two sets of water-tubes
connecting the headers and arranged in series leading from the plane of the grates
towards the boiler and forming parts of the inner walls of the fire-boxes, such
walls being spaced apart to form a flue registering with the aperture of the
partition, a series of tubes connecting the headers and crossing the upper portions
of the fire-boxes, and connection between the headers and the boiler.
5. In a down-draft furnace, the combination with an upper set of water-tube
grate-bars, of a lower set of water-tubes, the members of each set being vertically
alined, and mechanical connection between each of the lower tubes and the tube
immediately above it, whereby the lower set aids in supporting the fuel.
6. In a down-draft furnace, the combination with an upper set of water-tube
grate-bars, of a lower set of water-tubes, the members of each set being vertically
alined, masonry filling the interspace between the upper and lower members of
each pair of tubes, whereby the lower set aids in supporting the fuel.
7. In a down-draft furnace, the combination with an upper set of water-tube
grate-bars, of a lower set of water-tubes, the members of each set being vertically
alined, the lower tubes being of less diameter than the upper tubes, and mechanical
connection between each of the lower tubes and the tube immediately above it,
whereby the lower set aids in supporting the fuel.
8. In a steam generator, the combination with a pair of down-draft furnaces
spaced apart to form there-between a flue passage, and an up-draft furnace
located below and intermediate of the down-draft furnace, of rotatable cylinders
of refractory material at the sides of the up-draft furnace for receiving and deliver-
ing thereto material dropping from the down-draft furnaces.

page_text: 9. In a steam generator the combination with a boiler, and a furnace, of a
bridge-wall combining a metallic chest, and an inverted arch of masonry resting
upon such chest, and induction and eduction tubes connecting the chest with the
boiler.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.