CONNECTED WITH STEAM BOILERS AND THEIR APPLICABLE TO OTHER APPARATUS IMPROVEMENTS IN AND FURNACES AND IN PART
Year: 1883

page_text: LETTERS PATENT to Graham Stevenson, of Airdrie, in the County of Lanark,
North Britain, Engineer for an Invention of
CONNECTED WITH STEAM BOILERS AND THEIR
APPLICABLE TO OTHER APPARATUS
IMPROVEMENTS IN AND
FURNACES AND IN PART
PROVISIONAL SPECIFICATION left by the said Graham Stevenson at the
Office of the Commissioners of Patents on the 29th December 1883.
GRAHAM STEVENSON, of Airdrie, in the County of Lanark, North Britain,
Engineer, "IMPROVEMENTS IN AND CONNECTED WITH STEAM BOILERS AND THEIR
FURNACES AND IN PART APPLICABLE TO OTHER APPARATUS
"
This Invention has principally for its object to improve the construction of
steam boilers, to increase their efficiency, and to render them less liable to get out
of order, whilst some of the improvements comprised in the Invention are
advantageously applicable otherwise than to steam boilers and their furnaces.
A boiler made with the improvements according to one modification has an
upper horizontal cylindrical shell for the separation and collection of the steam
with the water level at about or a little above its middle, whilst the principal
heating surface is supplied by tubes having the water inside of them and which
are attached to the sides of the upper cylinder so as to extend downwards in
inclined directions and crossing each other beneath the cylinder in a heating
chamber enclosed by vertical walls. The tubes are attached by their sides to the
cylinder their upper ends extending out through the top of the heating chamber
and having bolted or screwed covers, whilst their lower ends extend through the
side walls and have bolted or screwed covers fitted with blow-off cocks. Each
tube is provided with an inner circulating pipe open at its bottom end and
communicating with the cylinder at its upper end; and the attachment of the
tube to the cylinder is effected by means of an internal distance piece which is
formed at its lower part with the communication for the circulating pipe, and with
a communication at its upper part for the passage of the upward current of water
and steam into the cylinder. The distance piece is also formed for the passage
through it of a bolt the head of which is at the outer side of the tube whilst its

page_text: screwed end passes through a cross bar inside of the cylinder and has a nut
screwed upon it on the inside of the bar. A suitably shaped washer is inserted
between the tube and the cylinder and the parts are drawn securely together by
means of the screw bolt. In some cases the inner circulating pipes may be
dispensed with, but the distance piece is by preference always made with upper
and lower openings into the cylinder to facilitate circulation. In some cases also
instead of the bolt passing through both sides of the tube it may be passed through
the inner side only, being made with a T head to be entered from the inside of the
cylinder through elongated holes and then turned a quarter round. The tubes
may be straight or curved; and when curved each may be attached to the cylindr
or other part of the boiler at more than one point. The improved mode of
attaching the tubes is applicable to any kind of steam boiler having tubes with
water inside of them.
The improved furnace is constructed on the regenerative system but with the
fire gases always passing in the same direction through the chamber or space in
which they act on the tubes or other part of the boiler. Two regenerative
chambers filled with the usual open brick checker-work are employed being
constructed side by side beneath the heating chamber or boiler and the fire grate
is arranged beneath or external to the regenerative chambers. A four-way valve
is according to one modification, arranged at each end and of one of these valves
one of the ways communicates with the chimney and another with an air inlet the
other two communicating with the regenerative chambers. Two of the ways of
the other valve also communicate with the regenerative chambers the remaining
two ways communicating one with the fire grate and the other with the heating
chamber which last communicates at its other end with the fire grate. The fire
gases proceed from the fire grate through the heating chamber thence through one
of the regenerative chambers to the chimney. When the regenerative chamber has
become heated the valves are changed (levers for working them being connected so
that they can be changed simultaneously) and the used gases are passed through
the other regenerative chamber. The air supplying the fire passes through which-
ever of the regenerative chambers is not being passed through by the used gases
and takes up and utilises the heat deposited therein.
The regenerative chambers are by preference formed in the two halves of a
horizontal cylindrical iron shell or in two separate horizontal cylindrical iron shells,
the shell or shells being lined with fire brick and fitted with removable ends to give
convenient access for cleaning; and they may be arranged at the sides of instead
of beneath the boiler or in any other convenient position. The valves are by
preference made to rotate on horizontal or other axes, and are lined with fire brick,
being arranged to cover ports of the various passages or flues in a disc-like port
face and being formed with cavities for putting various pairs of the ports in
communication.
The fire grate is provided with improved apparatus for supplying coal to it from
below. A truck arranged to pass under the grate bars is made with spaces for coal
formed between two semi-cylindrical shells, the tops of the spaces being directly
beneath openings left between the grate bars at each side of the middle. Between
the shells there are two pistons for pushing up the coal through the grate openings
and these two pistons are formed with curved racks guided one against the outer
semi-cylindrical shell and the other against the inner shell. The rack teeth face
each other and are acted upon by a single pinion placed between them. The teeth
of the pinion and racks are made of zig-zag form each tooth having a middle part
inclined in one direction and lateral parts inclined in the reverse direction an
arrangement which imparts increased strength to the teeth whilst promoting
smooth working.
Instead of burning the fuel in a grate in immediate connection with the boiler
gas from a gas producer may be employed or where available combustible or waste
gas from another furnace of any kind.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Graham Stevenson in the Patent Office on the 27th June 1884.
GRAHAM STEVENSON, of Airdrie, in the County of Lanark, North Britain,
Engineer "IMPROVEMENTS IN AND CONNECTED WITH STEAM BOILERS AND THeir
FURNACES AND IN PART APPLICABLE TO OTHER APPARATUS
"
My said Invention has principally for its object to improve the construction of
steam boilers, to increase their efficiency, and to render them less liable to get
out of order, whilst some of the improvements comprised in my Invention are
advantageously applicable otherwise than to steam boilers and their furnaces.
In particularly describing my improvements I will refer to two sheets of
explanatory drawings which are hereunto appended, premising that in these
drawings the same reference numerals are used to mark the same or like parts
wherever they are repeated.
A boiler made with my improvements according to one modification is shown in
transverse vertical section in figure, 1, of the accompanying drawings. It has an
upper horizontal cylindrical shell, 11, for the separation and collection of the steam,
with the water level at about, or a little above its middle, whilst the principal
heating surface is supplied by tubes, 12, having the water inside of them, and
which are attached to the sides of the upper cylinder, 11, so as to extend down-
wards in various directions some of them being inclined and crossing each other
beneath the cylinder, 11, in a heating chamber, 13, enclosed by vertical side
walls, 14, and a bottom horizontal partition, 15. The tubes, 12, are attached by
their sides to the cylinder, 11, their upper ends extending out beyond the top of
the heating chamber, and having bolted or screwed covers, whilst their lower
ends may extend through the side walls, 14, or as shown, through the bottom
partition, 15. One of the tubes, 12, is shown in longitudinal section and on an
enlarged scale in figure, 2. Each tube, 12, is provided with an inner circulating
pipe, 16, open at its bottom end and communicating with the cylinder, 11, at its
upper end; and the attachment of the tube to the cylinder is effected by means of
an internal distance piece, 17, which is formed at its lower part with the communi-
cation for the circulating pipe, 16, and with a communication, 18, at its upper part
for the passage of the upward current of water and steam into the cylinder, 11.
The distance piece, 17, is also formed for the passage through it of a bolt, 19, the
head of which is at the outer side of the tube, 12, whilst its screwed end passes
through a cross bar, 20, inside of the cylinder, 11, and has a nut screwed upon it
at the inside of the bar. A suitably shaped washer, 21, is inserted between the
tube, 12, and the cylinder, 11, and the parts are drawn securely together by means
of the screw bolt, 19. In some cases the inner circulating pipe, 16, may be
dispensed with, but the distance piece, 17, is by preference always made with
upper and lower openings into the cylinder, 11, to facilitate circulation. In some
cases also instead of the bolt, 19, passing through both sides of the tube, 12, it may
be passed through the inner side only, being made with a T head to be entered
from the inside of the cylinder, 11, through elongated holes and then turned a
quarter round. The tubes, 12, may be straight as shown or they may be curved;
and when curved each may be attached to the cylinder (11) or other part of the
boiler at more than one point. The improved mode of attaching the tubes is
applicable to any kind of steam boiler having tubes with water inside of them..
My improved furnace is constructed on the regenerative system but with the fire
gases always passing in the same direction through the chamber or space (13) in
which they act on the tubes or other part of the boiler. As my improvements in
connection with furnaces are applicable not only to steam-boiler furnaces but to

page_text: others, I have shown them in the drawings as applied to a reverberatory or heating
furnace, figure 3, being a longitudinal vertical section, and figure, 4, a transverse
vertical section, the latter section being as taken at one end of the furnace. Two
regenerative chambers, 22, 23, are employed consisting of horizontal iron cylinders
filled with the usual open brick checkerwork; and in the case of a steam boiler
such as is shown in figure, 1, they could conveniently be placed beneath the
heating chamber, 13. In the modification shown in figures, 3, and 4, the
regenerative chambers, 22, 23, are placed above the reverberatory chamber or
furnace, 24, and extend from end to end thereof. Four-way valve apparatus is
arranged at each end; and at one end the valve apparatus communicates with the
chimney, 25, and at the other end with air inlets, 26. The valves consist of four
pistons or disks, 27, working up and down in vertical cylindrical passages, 28,
across the openings at the ends of the regenerative chambers, 22, 23, the two at
one end being connected by a chain passing over a pulley, 29, and the two at the
other end being connected by a chain passing over another pulley, 30. The two
pulleys, 29, 30, are on shafts which are geared together so that the pulleys may
turn oppositely to each other. The combustible gas, supplied through a pipe and
casing which is not shown, enters the furnace, 24, by ports, 31, above which are
ports, 32, through which the air enters. This air first entering one of the
inlets, 26, passes through one of the regenerative chambers, 22, or 23, whilst the
used gases passing off from the other end of the furnace, 24, pass through
the other regenerative chamber to the chimney, 25. The valves, 27, are reversed
at suitable periods so that the air picks up the heat deposited by the escaping
gases in the regenerative chambers alternately.
When the steam boiler is heated by fuel burned in the ordinary way upon a
grate I apply in connection with such grate improved apparatus for introducing
the fresh fuel from below. Figure, 5, is a transverse vertical section showing the
application of this fuel feeding apparatus to a steam-boiler furnace. A truck
arranged to pass under the grate, 33, is made with spaces for coal formed between
two semi-cylindrical shells, 34, 35, the tops of the spaces being directly beneath
openings, 36, left between the grate, 33, and the sides of the furnace. Between
the shells 34, 35, there are two pistons, 37, 38, for pushing up the coal through
the openings, 30, and these two pistons are formed with curved racks, 39, 40,
guided one against the inner semi-cylindrical shell, 34, and the other against the
outer shell, 35. The rack teeth face each other and are acted on by a single
pinion, 41, placed between them. The teeth of the pinion, 41, and racks, 39, 40,
are made of zig-zag form each tooth having a middle part inclined in one direction
and lateral parts inclined in the reverse direction, an arrangement which imparts
increased strength to the teeth whilst promoting smooth working. In the present
application also the form of the teeth assists in guiding the racks.
The improved construction of pinion teeth is advantageously applicable
wherever strength combined with smooth working is desiderated, and examples
of its application are shown in figures, 6, and 7, each representing a pair of
pinions gearing together the two spindles of a rolling mill. In figure, 6, the teeth
are each continuous across the breadth of the pinion, whilst in figure, 7, the teeth
are shown divided round the middle. The improved construction of tooth is also
applicable to bevil wheels.
Having thus particularly described my said Invention and the manner of
performing the same I have to state that I do not restrict myself to the precise
details herein described or delineated but that what I believe to be novel and
original and claim as the Invention secured to me by and in terms of the herein-
before in part recited Letters Patent is :-
1. The improved construction of steam boiler hereinbefore described with
reference to figure, 1, of the accompanying drawings.
2. The improved construction of boiler tube (for having water inside) and the
improved mode of attaching the tube herein before described with reference to
figure, 2, of the accompanying drawings.

page_text: 3. The improved mode of constructing regenerative chambers combined with
the mode of arranging them in connection with steam-boiler or other furnaces
herein before described with reference to figures, 3, and 4, of the accompanying
drawings.
4. The improved fuel feeding apparatus hereinbefore described with reference to
figure, 5, of the accompanying drawings.
5. The improved form of gearing tooth herein before described with reference to
figures, 5, 6, and 7, of the accompanying drawings.
In Witness whereof I, the said Graham Stevenson have hereunto set my hand
and seal this twenty-fifth day of June in the year of our Lord One thousand eight
hundred and eighty-four.
Witness
EDMUND HUNT
Patent Agent
Glasgow.
GRAHAM STEVENSON
(L.S.)