Improvements in Steam Generators.
Year: 1897

page_text: Improvements in Steam Generators.
I, CHARLES ARTHUR ALLISON, Patent Agent, of 52 Chancery Lane, London, do
hereby declare the nature of this invention (which has been communicated to
me from abroad by Ellis Freeman Edgar, Engineer, of Woodbridge, in the County
of Middlesex and State of New Jersey, United States of America), and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement:-
The invention relates to boilers for generating steam.
In the accompanying drawings forming part of this specification;-
Figure 1, is a central vertical sectional view of a boiler embodying my invention,
some parts of the burner being in full view;
Figure 2, is a plan view of same;
Figure 3, is a sectional view of one form of burner I use when oil is the fuel;
Figure 4, is a similar view of a form of burner I use when the fuel is coal dust;
Figures 5 and 6, are detail views of the ends of the tubes I prefer to employ;
Figure 7, is a central sectional view of a boiler embodying my invention, but
having only one fire tube in which the draft is downward;
Figure 8, is an upper face view of the boiler of Figure 7; and
Figure 9, represents a modification in which horizontal burner tubes are
combined with upright fire tubes extending through the main water space of
the boiler.
For some uses especially in marine work, a boiler needs to be so constructed
that its center of gravity is low, and it can be placed in a boat so as to have her
center of gravity low, or to even lower it below the point where it was before the
boiler was shipped.
The boiler have invented and now describe is especially satisfactory in this
regard for it can be so arranged as to have no furnace (in the usual sense of the
term) at the bottom and will permit the weight to be brought well down.
This result, in some forms of boilers, is attained by putting the burners at the
top of the boiler and directing them downward, as shown in Figures 1 to 8, or it
may be attained by using vertical tubes surrounded by water in connection with
horizontal (or substantially horizontal) tubes for the burners, as shown in
Figure 9.
Instead of one long direct tube, I use comparatively short tubes, down and back
or in and up, or an equivalent, such as a long tube bent into U shape, either
combination giving a shorter boiler having a lower center of gravity.
I use comparatively large tubes and thereby avoid killing the flame from the
burners and at the same time ensure that a greater proportion of heat to the heating
surface shall enter the return or upright tubes than would be the case were they
quite small in diameter, as cross area increases faster than circumference.
Then to avoid losing all the heat thus forced into the return or upright tubes I
contract them at or about the water line, thereby causing the heat to be utilized
in heating the water and not merely pushed through to be lost in the stack or the
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page_text: outer air and I ensure the use of the heat by placing circulator tubes about the
fire tubes.
Provision for deflecting the flame in some forms is made, sometimes by the use
of a spatter plate and the plate is kept from excessive heating and the combustion
assisted by means of air led through passages into a combustion chamber and about
the spatter plate. The steam is kept dry by the use of a separating plate to be
described.
The combination results in a very effective boiler, but I do not limit my claim
to a boiler which possesses all of the advantages specified as some of the inventions
may be used and be of great service even though some other features were omitted
and I consider that my invention consists in devising a return tube boiler which
can be used vertically or one with horizontal and vertical tubes and in various
devices and combinations or devices which are useful in such a boiler (some may
be in others) and my claims will be more particularly specified hereafter.
The form shown in Figures 1 to 8 is that of a circular outer shell, S, provided
with an upper tube sheet S', and a lower sheet S2, in which a series of fire tubes T
and Tare set vertically, tubes T, being those or that part in which the draft is
intended to be downward to the lower combustion chamber C (each tube is also
in fact a combustion chamber) and tubes T" being the other part or the return
tubes leading from combustion chamber C to the smoke box B.
The proportion of one to the other may be varied but I have found in a boiler
feet high and 22 inches in diameter with tubes 5 inches in diameter 1 down to 6
up was satisfactory and in higher boilers say 6 feet, and 6 feet in diameter with 5
or 6 inch tubes 1 down to 2 or 4 up, though these proportions need not be rigidly
maintained.
If U shape tubes were used, there would of course be one down for each one up.
The return or outgoing vertical tubes I contract at or about the water line to
prevent the escape of the heat units and I prefer to do this by suspending in each
tube, by a hanger h, from a bar b, a fire clay wall or block W, of such size that the
united cross areas of the space between said walls W and the tubes T' shall
approximate the cross areas of the exit or exits of the smoke box, that is the stack,
though I do not limit myself to contracting the draft space in that manner.
It might be thought that such construction would so retard the draft as to impair
combustion but I find it otherwise. Using large tubes, flame and highly heated
air and gases enter them very rapidly, and they are much hotter than a small
tube would be but heat is also rapidly absorbed by the tubes and the water upon
their outer sides and as volume depends very largely upon heat I do not need as
great a space for the exit from the tubes as I do for the entrance and if I left it
of the same size I would be permitting large quantities of heat to pass beyond the
point where I can make it most useful.
The burners N, are located at the entrance or upper end of tubes T, preferably
several, and one for each tube, but I might substitute one large tube and burner
for the several I prefer.
ine burners shown are quite simple in construction having an inner tube t, for
the introduction of compressed air or steam, a so called combining chamber and
nozzle c, surrounding said tube having a fuel pipe f, for oil or coal dust, leading
into it and an air inlet nozzle i, surrounding the combining chamber. Any other
of the hundreds of such burners may be used in place of those shown.
These burners are directed downward and, in the form where the flames would
impinge upon the base plate or bottom wall wc, of chamber C, I place a spatter plate P,
made usually of fire clay (other substances might be used) to assist in spreading
the flames and deflecting them so that they will enter the return tubes with the
currents to the up take.
This plate P, is set on blocks and located over a hole cut through the bottom
wall w, and a space or passage is left or made between said plate and wall from the
hole in the wall to the chamber C, through which additional air enters to aid
the combustion within. This air passing along in contact with said plate will

page_text: itself become heated (an advantage) and by taking heat units from the plate will
increase its life.
As no ash pit, grate bars or large fuel space is required at the bottom of the
boiler, the combustion chamber C, if one is used, being much shallower than an
ordinary furnace, it is evident that my boiler may be set much lower and be much
shorter (up and down) than those of ordinary construction. I preferably guard
the mud legs by side walls w', or fire brick or fire clay.
The natural course of heat is of course upward and as the draft herein is first
downward and then upward, the natural force is at first acting against the force
with which the burning fuel is thrown into the tubes, which combination of
circumstances causes what I may term compression within the tubes and this
enhances the heat therein; likewise aided in the return tubes by the contraction
therein.
So great is the heat when thus enhanced that the boiler would in all probability
foam and prime were it not for the circulating tubes T2, which are a little larger
in diameter than the fire tubes but placed about them and set on feet or blocks or
otherwise raised a little from the lower tube sheet so that water may freely enter
them at the bottom and pass up between their interior faces and the outer faces of
the fire tubes, ensuring rapid continuous circulation.
These circulating tubes may be held in place concentric with the fire tubes by
fins, usually four at each end arranged within them; the four at the bottom
projecting a short distance beyond the circulating tube to hold the same up from
the tube sheet and thus allow for the entrance of water, and the height of the
circulating tubes is such that they terminate usually just above the water level.
A. smoke box B, (so called) is arranged above the ends of the return tubes, (here
in annular form to accommodate the form of the boiler) and provided with one
or more draft exits E (here 'two). A separating plate P', supported on lugs p to
which it is bolted, is interposed between the upper ends of the circulating tubes
and the steam exit that any water driven up by the very rapid circulation may not
pass off into the steam pipe but will fall back into and remain with the water of
the boiler, while the steam generated will be able to pass up through the space p
between the edge of the separating plate P' and the boiler shell.
The boiler of Figure 9, operates very much as those shown in the other figures
and is sometimes preferred where floor space is not so contracted. In the arrange-
ment of the outgoing vertical tubes, it does not differ from the forms above
described, except that all the vertical tubes are outgoing and the smoke box is
usually cylindrical with one exit instead of annular with two exits.
The incoming tubes as is manifest, are set substantially horizontal, projecting
into the combustion chamber, and there may be one or two or any desired number
of such incoming tubes. The boiler represented is supposed to have four.
Figure 9, being a central vertical sectional view, shows of course the end of one
and sections of two others, the fourth not being visible in such a view. If the
boiler is as high as seven feet, I prefer to use 7 inch vertical tubes and 12 inch
incoming tubes lined with fire clay about an inch and a half thick. These boilers
are very effective, simple to construct, durable, readily inspected and cleaned and
easily regulated as to the amount of fuel, the pressure to be employed to force it
to the point of ignition and the consequent volume of steam to be produced.
Having now particularly described and ascertained the nature of my said in-
vention and in what manner the same is to be performed, I declare that what
1 claim is :-
1. The combination in a vertical boiler, of a combustion chamber, a fire tube
leading to and opening into said chamber, a fire tube leading from said chamber
to the draft exit and a burner located at that end of the first fire tube opposite the
combustion chamber and directed substantially parallel to said fire tube and toward
said combustion chamber, all substantially as set forth.
2. The combination in a vertical boiler, of a combustion chamber, a fire tube

page_text: leading to and opening into said chamber, a fire tube leading from said chamber
to the draft exit and a burner located within that end of the first fire tube opposite
the combustion chamber and directed substantially parallel to said fire tube and
toward said combustion chamber, all substantially as set forth.
3. The combination in a vertical boiler of a combustion chamber, a fire tube
leading to and opening into said chamber, a fire tube leading from said chamber
to the draft exit, circulator tubes surrounding said fire tubes, and a burner located
at that end of the first fire tube opposite the combustion chamber and directed
substantially parallel to said fire tube and toward said combustion chamber, all
substantially as set forth.
4. The combination in a vertical boiler, of a combustion chamber, a fire tube
leading to and opening into said chamber, a fire tube leading from said chamber
to the draft exit, the draft space of which is contracted at or near the water level
of the boiler, and a burner located at that end of the first fire tube opposite the
combustion chamber and directed substantially parallel to said fire tube and toward
said combustion chamber, all substantially as set forth.
5. The combination in a vertical boiler, of a combustion chamber, a fire tubo
leading to and opening into said chamber, a fire tube leading from said chamber
to the draft exit, and provided with an incombustible block located within the tube
and at or near the water level and a burner located at that end of the first fire
tube opposite the combustion chamber and directed substantially parallel to said
fire tube and toward said combustion chamber, all substantially as set forth.
6. The combination in a vertical boiler, of a combustion chamber, a fire tube
leading to and opening into said chamber, a fire tube leading from said chamber
to the draft exit, circulator tubes surrounding said fire tubes, a separator interposed
between the upper end of the circulator tubes and the steam exit, and a burner
located at that end of the first fire tube opposite the combustion chamber and
directed substantially parallel to said fire tube and toward said combustion
chamber, all substantially as set forth.
7. The combination in a vertical boiler, of a combustion chamber, a fire tube
leading to and opening into said chamber, a fire tube leading from said chamber
to the draft exit, a burner located at that end of the first fire tube opposite the
combustion chamber and directed substantially parallel to said fire tube and
toward said combustion chamber and a spatter plate located in the combustion
chamber and opposite the nozzle of the burner, all substantially as set forth.
8. The combination in a vertical boiler, of a combustion chamber, a fire tube
leading to and opening into said chamber, a fire tube leading from said chamber
to the draft exit, a burner located at that end of the first fire tube opposite the
combustion chamber and directed substantially parallel to said fire tube and
toward said combustion chamber, a spatter plate located in the combustion chamber
and opposite the nozzle of the burner, one or more openings through the walls of
the combustion chamber and a passage between it and the spatter plate, all
substantially as set forth.
9. The combination in a vertical boiler, of a combustion chamber, a fire tube
leading to and opening into said chamber, a fire tube leading from said chamber
to the draft exit, a burner located at that end of the first fire tube opposite the
combustion chamber and directed substantially parallel to said fire tube and
toward said combustion chamber, and a substantially annular smoke box enclosing
the upper end of the fire tubes leading from the combustion chamber, all
substantially as set forth.
10. The combination in a vertical boiler, of a combustion chamber provided with
side and bottom walls, an opening through the bottom wall of the combustion
chamber, a passage between said wall and the spatter plate, a fire tube leading
to and opening into said combustion chamber, a fire tube leading from said
combustion chamber to the draft exit, a burner located at that end of the first
fire tube opposite the combustion chamber and directed substantially parallel
to said fire tube and toward said combustion chamber, and a substantially annular

page_text: smoke box enclosing the upper end of the fire tubes leading from the combustion
chamber and provided with a draft exit, all substantially as set forth..
11. The combination in a vertical boiler, of a combustion chamber, a fire tube
leading to and opening into said chamber, a fire tube leading from said chamber
to the draft exit, circulator tubes surrounding said fire tubes, and a nozzle burner
located within that end of the first fire tube opposite the combustion chamber and
directed substantially parallel to said fire tube and toward said combustion
chamber, all substantially as set forth.
12. The combination in a vertical boiler of a combustion chamber, a fire tube
leading vertically downward to and opening into said chamber, a fire tube leading
vertically upward from said chamber to the draft exit, circulator tubes surrounding
said fire tubes, and a burner located at that end of the first fire tube opposite the
combustion chamber and directed substantially parallel to said fire tube and
toward said combustion chamber, all substantially as set forth.
13. The combination in a vertical boiler, of a combustion chamber, a fire tube
above said combustion chamber and leading to and opening into said chamber, a
fire tube leading from said chamber to the draft exit and a burner located at that
end of the first fire tube opposite the combustion chamber and directed substantially
parallel to said fire tube and toward said combustion chamber all substantially as
set forth.
1 1
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1007
ALLISON
BROS.,
Agents for the Applicant.