IMPROVEMENTS IN STEAM BOILERS
Year: 1882

page_text: LETTERS PATENT to Graham Stevenson, of Airdrie, in the County of Lanark,
North Britain, Engineer, for an, invention of
BOILERS."
16 IMPROVEMENTS IN STEAM
PROVISIONAL SPECIFICATION left by the said Graham Stevenson at the
Office of the Commissioners of Patents on the 6th April 1882.
GRAHAM STEVENSON, of Airdrie, in the County of Lanark, North Britain,
Engineer, "IMPROVEMENTS IN STEAM BOILERS."
This Invention has for its object by improved modes of combining tubes, having
the water inside of them, with other parts, to form boilers which have extensive
heating surfaces of a very efficient character, which are of comparatively small size
and cost for their steam generating power, and which are extremely safe. The
Invention also comprises important novel arrangements of the furnaces and flues
of steam boilers, such arrangements having for their object the prevention or
consumption of smoke and the complete utilisation of the heat yielding power of
the fuel. With slight modifications of the arrangements the improved boilers
comprised in the Invention can be adapted for stationary, portable, locomotive, or
marine purposes; and they can be arranged for being heated by means of solid fuel
burned in furnaces forming part of their structures, or by means of combustible
gases produced for the purpose or of the waste gases of blast or other metallurgical
furnaces.
In one modification of steam boiler as constructed according to the present
Invention a number of horizontal tubes are placed so as to form a horizontal or
nearly horizontal series, being nearly in contact with each other, and being
supported by outer brick walls through which their ends project. The series of
tubes cover a rectangular space divided by brick walls into various flues and
furnace spaces which may be described as being longitudinal whilst the tubes are
transverse, so that the currents of the fire gases are (for the most part) at right
angles to the tubes, on which the gases will impinge as upon a corrugated surface
and which will on that account form very efficient heating surfaces. There are
two furnace spaces one being on each side of a central flue, and the inner ends of
TD

page_text: these furnace spaces communicate by a flue crossing under the central flue. The
front end of the central flue communicates with a transverse flue crossing the front
ends of the furnace spaces at a level below the fire bars; and valves are provided
for opening and closing the communications with the front transverse flue so as to
carry out the improved system of working whereby it is believed the complete
utilisation of the fuel will be obtained without smoke. In one simple modification
of the valve details, a pinion worked by means of a single external handle gears
with a rack fixed to a compound slide formed with horizontal plates and vertical
plates or doors for closing the various communications, the slide being moved from
side to side and at each movement opening certain communications at one side and
at the same time closing the corresponding ones at the other side. Thus, in one
position of the compound slide the communications of the right-hand furnace with
the front transverse flue, and of that flue with the central flue are closed, whilst
those of the left-hand furnace are opened. This is the position when fresh fuel
is in the right-hand furnace, and the gases from it have then to pass backward and
through the inner cross flue to the left-hand furnace in which latter the fuel will
be incandescent or in an advanced state of combustion such as to insure the
ignition of any combustible constituents of the gases passing over or through it
from the other furnace. From the left-hand furnace the combined gases of the
two furnaces pass by the front transverse flue into the central longitudinal flue;
and when the time arrives for supplying fresh fuel to the left-hand furnace then
the valves are reversed and the gases from the left-hand fornace will pass back-
wards and across to the right-hand furnace and the combined gases will pass over
or through this latter and by the front transverse flue to the central longitudinal
flue. The compound valve slide has by preference combined with it slides having
plates or doors for closing the inlets for air into the ash pits of the furnaces, and
adjustable gratings or valves by means of which the quantity of air admitted to
the ash pit can be regulated. The central flue extends to the back end of the
series of tubes and there divides into two flues returning towards the furnaces
and afterwards proceeding backwards again to a flue or flues leading to the
chimney. The arrangement of these flues may however be varied in different
cases.
• The tubes which may be of steel, malleable iron, or brass, are fitted with
removable covers at both ends, to allow of their being seen through and of their
being easily and thoroughly cleaned when required. Both ends of the tubes are
connected to pipes or casings communicating with one or more cylinders or drums
placed at a higher level than the tubes and serving as steam receivers although
being always partly filled with water. The fittings at the ends of the tubes may
be varied, but in one inexpensive yet safe and convenient modification there is cast
or otherwise fixed on each end of each tube an iron casting of a square form
externally and made with slotted projections extending beyond the ends of the
tube to receive a wedge key which is used to secure a cap or door against the end
of the tube. Each cap or door is made with an annular groove to fit on the end
of the tube and a ring of copper or lead or of a suitable composition is placed in
the groove to make a tight joint when the cap or door is wedged home. The
square end castings rest upon or are fixed up against a planed surface formed for
the purpose on the casing which forms the communication between the tubes and
the steam cylinder or cylinders; and the tubes are fixed to the casing by means
of clamps secured and tightened up by screw nuts, the tubes communicating with
the casing by ports formed in the joint surfaces. Ports may be made in opposite
or different sides of the square end castings to allow of a tube being turned if
found desirable after being in use for any time, those ports being closed with screw
plugs through which communication is not needed. In another modification. caps
.or covers are fixed on the ends of the tubes by nuts screwed on longitudinal bolts
the inner ends of which are riveted to the sides of the tubes, and the communi-
cations are made by means of pipes fixed to the caps or covers.
."
There may be one, two, or more horizontal or inclined series or sets of the

page_text: transverse horizontal tubes; and in some cases the tubes of a set instead of being
all horizontal and parallel to each other may have slight inclinations from the
horizontal in alternately opposite directions to promote circulation of the water;
or all those of a set or series or any number of them may have a similar slight
inclination for the same purpose. Where there are two or more sets of the tubes
or where there is a flue immediately above a set of tubes as well as below them
the spaces between the tubes of a set may be closed with fireclay; but where
there is no flue passing over the tubes those spaces need not be closed, but there
must of course be a fireclay or brickwork or other suitable cover above the tubes.
In one arrangement with two horizontal sets of tubes the fire gases from one
furnace pass under the lower tubes to the back end, then return between the lower
and upper tubes and enter the other furnace through a valve, the combined gases
of the two furnaces passing back through a separate flue under the lower tubes
and returning between the two sets of tubes. Afterwards the gases may be passed
through higher or other flues having tubes across them; and finally before being
led to the chimney they may be passed through. spaces surrounding the steam
cylinder or cylinders; but it is in all cases arranged that the fire gases shall act
on the steam cylinders only. after being considerably spent. In some cases instead
of there being one or two cylinders or drums for steam of larger size than the
tubes forming the main heating surface of the boiler, a number of tubes of the
same size or nearly so may be combined to form the upper part and steam space of
the boiler.
Instead of the horizontal tubes being carried near their outer ends by brick
walls, or even when such walls or fireclay slabs or linings are used, the ends of the
tubes may in some cases, as for example for locomotive and marine purposes, be
fixed in the inner sides of lateral water casings in the manner in which ordinary
flue tubes are fixed in boiler tube plates, the casings being provided at their outer
sides with bolted-on covers for giving access to the ends of the tubes.
In a modification suitable for utilising the waste fire gases from a puddling or
other metallurgical furnace a rectangular brickwork enclosure is formed, at two
opposite sides of which vertical sets or series of the horizontal tubes are placed
their ends projecting through the walls of the two other sides. With these tubes
there are combined horizontal sets of two, three, or more of the tubes arranged to
leave openings alternately at the opposite sides so that the fire gases entering at
the bottom pursue an upward zig-zag course between the various sets of tubes.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Graham Stevenson in the Great Scal. Patent Office on the
4th October 1882.
GRAHAM STEVENSON, of Airdrie, in the County of Lanark, North Britain,
Engineer, "IMPROVEMENTS IN STEAM BOILERS."
My said Invention has for its object by improved modes of combining tubes,
having the water inside of them, with other parts, to form boilers which have
extensive heating surfaces of a very efficient character, which are of comparatively
small size and cost for their steam generating power, and which are extremely
safe. My Invention also comprises important novel arrangements of the furnaces
and flues of steam boilers, such arrangements having for their object the prevention
or consumption of smoke and the complete utilisation of the heat yielding power
of the fuel. With slight modifications of the arrangements the improved boilers
comprised in my Invention can be adapted for stationary, portable, locomotive, or
marine purposes; and they can be arranged for being heated by means of solid fuel
burned in furnaces forming part of their structures, or by means of combustible
gases produced for the purpose or of the waste gases of blast or other metallurgical
furnaces.
In one modification of steam boiler as constructed according to my present
Invention a number of horizontal tubes are placed so as to form a horizontal or
nearly horizontal series, being nearly in contact with each other, and being
supported by outer brick walls through which their ends project. The series of
tubes cover a rectangular space divided by brick walls into various flues and
furnace spaces which may be described as being longitudinal whilst the tubes are
transverse, so that the currents of the fire gases are (for the most part) at right
angles to the tubes, on which the gases will impinge as upon a corrugated surface
and which will, on that account form very efficient heating surfaces. There are
two furnace spaces one being on each side of a central flue, and the inner ends of
these furnace spaces communicate by a flue crossing under the central flue. The
front end of the central flue communicates with a transverse flue crossing the front
ends of the furnace spaces at a level below the fire bars; and valves are provided
for opening and closing the communications with the front transverse flue, so as to
carry out the improved system of working whereby it is believed the complete
utilisation of the fuel will be obtained without smoke. In one simple modification
of the valve details, a pinion worked by means of a single external handle gears
with a rack fixed to a compound, slide formed with horizontal plates and vertical
plates or doors for closing the various communications, the slide being moved from
side to side and at each movement opening certain communications at one side and
at the same time closing the corresponding ones at the other side. Thus, in one
position of the compound slide the communications of the right-hand furnace with
the front transverse flue, and of that flue with the central flue are closed, whilst
those of the left-hand furnace are opened. This is the position when fresh fuel is
in the right-hand furnace, and the gases from it have thien to pass backward and
through the inner cross flue to the left-hand furnace in which latter the fuel will
be incandescent or in an advanced state of combustion such as to insure the
ignition of any combustible constituents of the gases passing over or through it
from the other furnace. From the left-hand furnace the combined gases of the two
furnaces pass by the front transverse flue into the central longitudinal flue; and
when the time arrives for supplying fresh fuel to the left-hand furnace then the
valves are reversed and the gases from the left-hand furnace will pass backwards

page_text: and across to the right-hand furnace and the combined gases will pass over or
through this latter and by the front transverse flue to the central longitudinal flue.
The compound valve slide has by preference combined with it slides having plates
or doors for closing the inlets for air into the ash pits of the furnaces, and
adjustable gratings or valves by means of which the quantity of air admitted to
the ash pit can be regulated. The central flue extends to the back end of the
series of tubes and there divides into two flues returning towards the furnaces and
afterwards proceeding backwards again to a flue or flues leading to the chimney.
The arrangement of these flues may however be varied in different cases.
The tubes which may be of steel, malleable iron, or brass, are fitted with
removable covers at both ends, to allow of their being seen through and of their
being easily and thoroughly cleaned when required. Both ends of the tubes are
connected to pipes or casings communicating with one or more cylinders or drums
placed at a higher level than the tubes and serving as steam receivers although
being always partly filled with water. The fittings at the ends of the tubes may
be varied, but in one inexpensivo yet safe and convenient modification there is
cast or otherwise fixed on each end of each tube an iron casting of a square form
externally and made with slotted projections extending beyond the ends of the
tube to receive a wedge key which is used to secure a cap or door against the
end of the tube. Each cap or door is made with an annular groove to fit on the
end of the tube and a ring of copper or lead or of a suitable composition is placed
in the groove to make a tight joint when the cap or door is wedged home. The
square end castings rest upon or are fixed up against a planed surface formed for
the purpose on the casing which forms the communication between the tubes and
the steam cylinder or cylinders; and the tubes are fixed to the casing by means of
clamps secured and tightened up by screw nuts, the tubes communicating with the
casing by ports formed in the joint surfaces. Ports may be made in opposite or
different sides of the square end castings to allow of a tube being turned if found
desirable after being in use for any time, those ports being closed with screw plugs
through which communication is not needed. In another modification caps or
covers are fixed on the ends of the tubes by nuts screwed on longitudinal bolts the
inner ends of which are riveted to the sides of the tubes, and the communications
are made by means of pipes fixed to the caps or covers.
There may be one, two, or more horizontal or inclined series or sets of the
transverse horizontal tubes; and in some cases the tubes of a set instead of being
all horizontal and parallel to each other may have slight inclinations from the
horizontal in alternately opposite directions to promote circulation of the water;
or all those of a set or series or any number of them may have a similar slight
inclination for the same purpose.
Where there are two or more sets of the tubes or
where there is a flue immediately above a set of tubes as well as below them the
spaces beeween the tubes of a set may be closed with fireclay; but where there is
no flue passing over the tubes those spaces need not be closed, but there must of
course be a fireclay or brickwork or other suitable cover above the tubes. In one
arrangement with two horizontal sets of tubes the fire gases from one furnace pass
under the lower tubes to the back end, then return between the lower and upper
tubes and enter the other furnace through a valve, the combined gases of the two
furnaces passing back through a separate flue under the lower tubes and returning
between the two sets of tubes. Afterwards the gases may be passed through
higher or other flues having tubes across them; and finally before being led to the
chimney they may be passed through spaces surrounding the steam cylinder or
cylinders; but it is in all cases arranged that the fire gases shall act on the steam
cylinders only after being considerably spent. In some cases instead of there being
one or two cylinders or drums for steam of larger size than the tubes forming the
main heating surface of the boilor, a number of tubes of the same size or nearly
so may be combined to form the upper part and steam space of the boiler.
Instead of the horizontal tubes being carried near their outer ends by brick
walls, or even when such walls or fireclay slabs or linings are used, the ends of the

page_text: tubes may in some cases, as for example for locomotive and marine purposes, be
fixed in the inner sides of lateral water casings in the manner in which ordinary
flue tubes are fixed in boiler tube plates, the casings being provided at their outer
sides with bolted-on covers for giving access to the ends of the tubes,
In a modification suitable for utilising the waste fire gases from a puddling or
other metallurgical furnace a rectangular brickwork enclosure is formed, at two
opposite sides of which vertical sets or series of the horizontal tubes are placed
their ends projecting through the walls of the two other sides. With these tubes
there are combined horizontal sets of two, three, or more of the tubes arranged to
leave openings alternately at the opposite sides so that the fire gases entering at the
bottom pursue an upward zig-zag course between the various sets of tubes.
Persons skilled in constructing steam boilers will have no difficulty in practically
carrying out my improvements from the herein before contained description of
them; I have however considered it useful to supplement the said description by
appending two sheets of explanatory drawings to be hereinafter referred to and
illustrating one or two of the numerous modifications of steam boilers which may
be constructed in accordance with my said Invention.
Figure, 1, on sheet 1, of the accompanying drawings is an end elevation of one
modification of my improved steam boilers; figure, 2, is a sectional side elevation;
and figure, 3, is a horizontal section. Figures 4, 5, and 6 are enlarged views
showing one of my modes of closing the ends of the tubes and connecting them to
the lateral casings or pipes. Figures, 7, and 8, on sheet, 2, are vertical and horizontal
sections of a second modification and figures, 9, and 10, are longitudinal and
transverse vertical sections showing the application of my improved furnace
arrangements to an ordinary horizontal cylindrical boiler. In these drawings the
same reference numerals are used to mark the same or like parts wherever they
are repeated.
In the boiler shown in figures, 1, 2, 3, the main heating surface is formed by a
number of transverse horizontal tubes, 11, arranged in a horizontal series, and, in
this example, having spaces between them. These transverse tubes, 11, are
connected to lateral casings, 12, which communicate with a cylinder; 13, a large
part of which last forms the steam space. The formation of the ends of the
tubes, 11, and their connections with the lateral casings, 12, will be understood
from figures 4, 5, 6, and from the description already given. The flues are
.constructed as shown in figure, 2, so that the fire gases pass alternately upwards
and downwards through the spaces between successive sections of the tubes; whilst
vertical partitions divide the flues in the manner shown in figure, 3, and so that
with the aid of certain movable valves, the gases from each of the two grates, 14, 15,
pass at alternate intervals through the fuel on the other grate. The fire bars are
by preference tubular and have water flowing continuously through them. There
is a middle flue, 16, between the two grate chambers, 14, 15, and the combined
gases from the two furnaces pass through this flue and thence by the tortuous
flues, 17, 18, 19, 20, 21, to the chimney, 22. The furnace chambers, 14, 15,
communicate by ports, 23, 24, at their inner ends with a low transverse flue, 25,
crossing below the middle flue, 16, which communicates at its front end with the
ash pits of the furnaces by ports, one, 26, of which is seen in figure, 2. A valve
plate, 27, is used for closing one of these ports, 26, being fixed to a front vertical
plate, 28, which is arranged to move on rollers from side to side at the front end of
the boiler, and which is formed with or has fixed to it a rack having gearing with
it a pinion, 29, The pinion, 29, can be turned by means of a winch handle, 30, for
moving the plate, 28, to one side or the other; and this plate is formed with closed
parts which cover the openings into the ash pits whilst other parts are formed or
fitted with permanent or adjustable perforations or inlets for admitting suitable
proportions of air to the ash pits. When the valvo plate, 27, is in a position for
closing the port, 26, from the middle flue, 16, into one ash pit, then the plate, 28, is
in the position for admitting air into that ash pit and excluding it from the other
one and vice versa. As shown in figures, 1, 2, 3, the passages are arranged so that

page_text: the fire gases from one fire pass by the transverse flue, 25, to the inner end of the
other fire and down through the bars of the other fire to the port, 26, and middle
flue, 16; but if preferred they may be arranged so that the fire gases from one fire
do not pass through the fire bars of the other fire but through a port leading
directly into the front end of the space above the bars and thence to middle
flue, 16.
In the modification shown in figures, 7, and 8; a horizontal valve slide, 31, for
changing the directions of the fire gases is arranged at the inner end of the furnace.
chambers, 14, 15, which are placed close together without having the middle
flue (16) between them. With the valve slide, 31, in the position shown in
figure, 8, the fire gases from the furnace, 15, supposed to be freshly charged with
fuel, pass by a port, 32, into a low flue and thence enter by a port at the front
end of the other furnace, 14; and the combined gases from this pass by a port, 33,
into a low flue communicating with the flues, 17, 18, 19, leading to the chimney, 22.
When the valve slide, 31, is shifted into its other position, the gases from the
furnace, 14, are led through ports and passages to the front end of the other
furnace, 15, from which the combined gases then pass to the flue, 17.
The furnace arrangements shown as applied to an ordinary boiler in figures, 9,
and 10, are the same as those herein before described with reference to figures, 7,
and 8.
Having thus particularly described my said Invention and the manner of per-
forming the same I have to state that what I believe to be novel and original and
claim as the Invention secured to me by and in terms of the hereinbefore in part
recited 'Letters Patent is ;-
1. The arranging or combining together of tubes having the water inside of them
with other parts to form steam boilers in any of the improved modes hereinbefore
described.
2. The constructing or arranging of steam-boiler furnaces, flues, and accessory
parts so that the fire gases from a furnace freshly charged with fuel may pass
through another furnace in which the fuel is in an advanced state of combustion
substantially as and for the purposes herein before described.
In Witness, whereof, I, the said Graham Stevenson have hereunto set my
hand and seal this second day of October in the year of our Lord One
thousand eight hundred and eighty-two.
Witness.
EDMUND HUNT.
Patent Agent.
Glasgow.
GRAHAM STEVENSON. (L.S.)