IMPROVEMENTS IN STEAM GENERATORS AND ENGINES
Year: 1879

page_text: LETTERS PATENT to Dugald Clerk, of Glasgow, in the County of Lanark, North
Britain, Analytical Chemist, for the Invention of "IMPROVEMENTS IN STEAM
GENERATORS AND ENGINES,"
AL
Sealed the 12th December 1879, and dated the 18th June 1879.
PROVISIONAL SPECIFICATION left by the said Dugald Clerk at the Office of
the Commissioners of Patents on the 18th June 1879.
DUGALD CLERK, of Glasgow, in the County of Lanark, North Britain, Analytical
Chemist. "IMPROVEMENTS IN STEAM GENERATORS AND ENGINES."
This Invention has for its object to construct a combined steam generator and
engine suitable for small powers, although not exclusively so, and extremely safe,
whilst very simple and not liable to derangement.
The steam generator and engine are arranged so that little or no water remains
permanently in the generator, a pump forcing water into the generator precisely in
proportion to the action of the engine, and in such a manner that if the engine is
at any time stopped without stopping the application of the heat there will not
be in the generator as much steam or water as can possibly give rise to a dangerous
pressure by the continued application of the heat. The pump is so connected to
the engine details that water cannot be pumped into the generator without at the
same time opening a valve, by which steam corresponding to the water injected by
pump finds its way to the engine or otherwise out of the generator.
the
The generator is constructed for being heated by means of gas, and in one modi-
fication there is a series of horizontal annular pipes of graduated sizes and
diameters, the smaller ones being lower in order. These annular pipes are fitted
with short straight supply pipes, having nozzles supplied by gas pipes inserted into
their outer ends, whilst air to mix with the combustible gas enters by alota or
apertures in the straight pipes. Jets of the mixed gas and air issue from and are
ignited at perforations at the upper inner sides of the annular pipes, and form a
D

page_text: number of cones of flame, which rise up into a central opening in the bottom of the
generator. The generator consists of a number of pieces or sections united at
horizontal or nearly horizontal joint surfaces, and fixed together by vertical bolts
or screws. The bottom or first section is formed with the central opening already
referred to, and with an annular space, which constitutes a small reservoir for steam.
The second or next higher section is made with an annular bottom part covering
the annular steam reservoir in the first section, and this annular part is connected
by tubular pillars to a disc-shaped top. The flames or fire gases rising up the
centre spread towards the outside under the disc-shaped top of the second section,
and finding their way upwards through openings at the outer edge return towards
the centre again in the third section, but as it were inverted. The fourth section
is partly like the second (without being inverted), and in it the flames or fire gases
again diverge from the centre to the outside. The fifth section is principally a
cover, but has at its centre the detail through which the water enters the generator.
The flames or fire gases converge from the outside over the fifth section, and the
waste gases pass off by a central vertical smoke pipe fitted to the top of a casing
used to cover or enclose the generator, and which casing consists by preference of
two metal shells, having the space between them filled with a non-conducting sub-
stance. The number of sections may be increased by interpolating one or more
additional couples, like that formed by the second and third sections.
The water forced in by the pump enters the generator by an annular spreader
constructed to convert it into fine spray. The inlet pipe projects down internally
from the cover or top section, and a disc or cup is screwed to it, the joint surfaces
between the two being horizontal and made very true so as to form a tight joint,
excepting a number of fine radial grooves filed in one of both of them. These fine
radial grooves form the passages for the water which issues from them in extremely
miniature jets, and breaks easily into fine spray, thereby facilitating the rapid
generation of steam. The water thus injected and any steam immediately formed
from it spread radially through a thin space formed between the top or fifth section
and the fourth, and then descend by small holes to a thin annular space between
the fourth and third sections. In this space there is an annular plate, which makes
the water and steam proceed first towards the centre and then return outwards to
a number of holes leading down to a thin space between the third and the second
sections, in which space they are again led by a plate, first towards the centre and
then outwards again. Finally, the steam with any water still unconverted passes
down a number of holes to the bottom of the second section, and after being led, an
annular plate in close proximity with the part of the second section covering the
annular space or reservoir enters this reservoir, whence it is conveyed by a pipe or
passage to the engine. With the described arrangements the water spray is led
in contact with a series of metal surfaces very strongly heated by the gas flames, and
steam is in consequence very rapidly generated.
The engine details to be worked by the steam thus generated may be of any con-
venient known kind, provided they comprise a pump to inject the water into the
generator in the manner hereinbefore explained. It is however preferred to com-
bine with the generator a single-acting cylinder fitted with a trunk piston, having
directly jointed to it a connecting rod, which imparts motion to a crank shaft having
a flywheel on it. The cylinder is inverted, and steam is admitted to it by a simple
lift valve at its upper end, and raised by the piston itself when at the top of its
stroke. The exhaust port is in the piston, and is controlled by a cover or valve on
the upper and inner side of the piston, this valve being worked by a short arm on
the end of the connecting rod.
The Invention comprises a second modification of the steam generator, which is
of an inverted conical form, and consists of a hollow conical metal casting, having
a helical groove formed on its outer surface, which is covered by a shell of copper
or other suitable metal. A helical pipe surrounds the copper shell conveying mixed
gas and air which issues from and is burned at a series of perforations in the

page_text: helical pipe so as to heat the copper shell. The water is injected into the top of
the generator by a spray producing spreader like that of the first modification, and
spreading over the top of the inner casting finds its way into and down the helical
passage formed between the groove and the copper shell. The steam generated
passes by perforations into the interior of the internal casting, and is thence led by
a pipe to the engine.
By a third modification the heating apparatus is arranged within a copper cone,
having its smaller end upwards, the generator being in an annular form, and con-
sisting partly of a casting fitting the copper cone, and grooved to form a helical
passage by which the water is led in contact with the cone.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Dugald Clerk in the Great Seal Patent Office on the 17th
December 1879.
'
DUGALD CLERK, of Glasgow, in the County of Lanark, North Britain, Analytical
Chemist. "IMPROVEMENTS IN STEAM GENERATORS AND ENGINES."
.
My said Invention has for its object to construct a combined steam generator
and engine suitable for small powers, although not exclusively so, and extremely
safe whilst very simple and not liable to derangement.
The steam generator and engine are arranged so that little or no water remains
permanently in the generator, a pump forcing water into the generator precisely
in proportion to the action of the engine, and in such a manner that if the engine
is at any time stopped without stopping the application of the heat there will not
be in the generator as much steam or water as can possibly give rise to a dangerous
pressure by the continued application of the heat. The pump is so connected to
the engine details that water cannot be pumped into the generator without at the
same time opening a valve, by which steam corresponding to the water injected
by the pump finds its way to the engine or otherwise out of the generator.
The steam generator is constructed for being heated by means of gas, and as
hereinafter particularly described with the aid of an accompanying Sheet of
explanatory Drawings. The engine details to be worked by the improved generator
may be of any convenient known kind, provided they comprise a pump to inject
the water into the generator in the prescribed manner. I have however combined
with the steam generator a special simple arrangement, comprising a single-acting
cylinder and peculiar valve details, also shown in the accompanying Drawings and
hereinafter particularly described. In these Drawings the same reference numerals
are used to mark the same or like parts wherever they are repeated.
Figure 1 of the Drawings is a vertical section of the combined steam generator
and engine, and Figure 2 is a sectional plan of the engine; Figure 3 is a vertical
section of a modification of the steam generator; Figures 4 and 5 are a plan and
vertical section enlarged, showing the exhaust-valve details of the engine.
In the modification of the steam generator, shown in Figure 1, there is a series
of horizontal annular pipes 6, of graduated sizes and diameters, the smaller ones
being lower in order. These annular pipes 6 are fitted with short straight supply
pipes 7, having nozzles 8 supplied by gas pipes inserted into their outer ends,
whilst air to mix with the combustible gas enters by slots or apertures in the
straight pipes 7. Jets of the mixed gas and air issue from and are ignited at per-
forations at the upper inner sides of the annular pipes and form a number of cones
of flame, which rise up into a central opening 9 in the bottom of the generator.
The generator consists of a number of pieces or sections 10, 11, 12, 13, 14, united
at horizontal or nearly horizontal joint surfaces, and fixed together by vertical bolts
or screws. The bottom or first section 10 is formed with the central oponing 9,
already referred to, and with an annular space 15, which constitutes a small
reservoir for steam. The second or next higher section 11 is made with an annular
bottom part covering the annular steam reservoir 15 in the first section, and this
annular part is connected by tubular pillars to a disc-shaped top 16. The flames
or fire gases rising up the centro 9 spread towards the outside under the disc-shaped
top 16 of the second section 11, and finding their way upwards through openings
at the outer edge return towards the centre again in the third section 12, which is
similar to the second section, but as it were inverted. The fourth section 13 is
partly like the second (without being inverted), and in it tho flames or fire gases
again diverge from the centre to the outside. The fifth section 14 is principally a
cover, but has at its centre the detail 17 through which the water enters the
generator. The flames or fire gases converge from the outside over the fifth section,
and the waste gases pass off by a central vertical smoke pipe 18, fitted to the top

page_text: of a casing 19 used to cover or enclose the generator, and which casing consists by
preference of two metal shells having the space between them filled with a non-
conducting substance. The number of sections may be increased by interpolating
one or more additional couples like that formed by the second and third sections,
11, 12.
The water forced by pumps 20 and conveyed by a pipe 21 enters the generator
by an annular spreader, constructed to convert it into fine spray. The inlet pipe 17
projects down internally from the cover or top section 14, and a disc or inverted
cap is screwed to it, the joint surfaces between the two being horizontal and made
very true so as to form a tight joint excepting a number of fine radial grooves filed
in one or both of them. These fine radial grooves form the passages for the water
which issues from them in extremely minute jets and breaks easily into fine spray,
thereby facilitating the rapid generation of steam. The water thus injected, and
any steam immediately formed from it spread radially through a thin space formed
between the top or fifth section 14 and the fourth 13, and then descend by small
holes in the connecting pillars to a thin annular space between the fourth and third
sections 13, 12. In this space there is an annular plate which makes the water
and steam proceed first towards the centre, and then return outwards to a number
of holes leading down through the connecting pillars thin space between the third
and the second sections 12, 11, in which space they are again led by a plate first
towards the centre and then outwards again. Finally, the steam with any water
still unconverted passes down a number of holes in the connecting pillars to the
bottom of the second section 11, and after being led by an annular plate in close
proximity with the part of the second section 11, covering the annular space or
reservoir 15, enters this reservoir, whence it is conveyed by a pipe or passage 22
to the engine. With the described arrangements the water spray is led in contact
with a series of metal surfaces very strongly heated by the gas flames, and steam is
in consequence very rapidly generated.
The steam generator is fixed down on a casting 23, which is itself bolted to the
top of the steam-engine cylinder 24, and which is formed with a chamber through
which the steam entering by the pipe 22 has access to the cylinder 24. In the
bottom of the chamber, which bottom forms the top of the cylinder 24, there is
fitted a simple conical lift valve 25 provided with a spring to insure its rapid
closing, and made with a stem projecting down, so as to be encountered by the
piston 26 when this piston moves up to the top of its stroke. The piston 26 is of
the trunk or elongated class, and is connected by a rod 27 to a crank on a horizontal
shaft 28, which shaft is at one end fitted with a flywheel pulley 29 to receive a
belt for transmitting the power developed by the engine. The other end of the
crank shaft 28 is formed or fitted with cranks or eccentrics 30 for working the
pumps 20, and with a handle 31. The crank of the shaft 28 is enclosed in a con-
tinuation 32 of the casting comprising the cylinder 24, and this casting is bolted
down on the top of a hollow pedestal 33 forming a reservoir for water, from which
the pumps draw by a pipe 34, and at the same time a receptacle or condenser for the
exhaust steam. The steam exhausts from the cylinder 24 down through ports in the
piston 20 itself, which ports are closed and opened as required by an angular move-
ment of a valve disc 35, Figures 4, 5, fitted on the upper side of the piston. The
connecting rod 27 has formed on it a short arm 36 projecting upwards from the
boss, by which the rod is pin-jointed to the piston; and this arm 36 projects up
through a slot in the piston into a notch formed in the underside of the valve
disc 35. With this arrangement the angular movement of the connecting rod 27
imparts a suitable movement to the valve disc 35, this movement being such as to
cause the shaft 28 to rotate always in the same direction.
The modification of the steam generator shown in Figure 8 is of an inverted
conical form, and consists of a hollow conical metal casting 37 having a helical
groove formed on its outer surface, which is covered by a shell 38 of copper or.
other suitable metal. A helical pipe or a series of annular pipes 6 surround the
copper shell 38 conveying mixed gas and air, which issues from and is burned at a

page_text: series of perforations in the pipe or pipes 6, so as to heat the copper shell. The
water is injected into the top of the generator by a spray producing spreader 17
like that of the first modification, and spreading over the top of the inner casting 37
finds its way into and down the helical passage formed between the groove and the
copper shell 38. The steam generated passes by perforations into the interior of
tho internal casting 37, and is thence led through the valve 25 to the engine.
By a third modification the heating apparatus is arranged within a copper cone
having its smaller and upwards, the generator being in an annular form, and con-
sisting partly of a casting fitting the copper cone and grooved to form a helical
passage, by which the water is led in contact with the cono.
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 and 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 combination of parts herein before described with reference to Figures
1, 2, 4, 5, of the accompanying Drawings, and constituting an improved combined
steam generator and engine.
2. The combination of parts hereinbefore described with reference to Figure 1 of
the accompanying Drawings, and constituting an improved steam generator to be
heated by combustible gas and air.
3. The herein before described construction of the inlet piece 17 for injecting the
water into the steam generator in the form of fine radiating jets and spray.
4. The constructing of the steam generator in sections, with passages for the
flame or fire gases to alternately diverge and converge, and with thin spaces for the
water and steam, all arranged and combined substantially as bereinbefore described
with reference to Figure 1 of the accompanying Drawings.
5. The constructing of the steam generator substantially as herein before described
with reference to Figure 3 of the accompanying Drawings, or with the heating
parts internal and the vessel in an annular form, also hereinbefore described.
6. The combination of parts herein before described with reference to Figures
1, 2, 4, 5, and constituting the steam-engine or motor details.
7. The herein before described combination of valve details for admitting tho
steam to and exhausting it from the cylinder.
8. The herein before described arrangement of the exhaust valve, comprising a port
or ports through the piston and an angularly moving valve worked by the angular
movement of the connecting rod.
In witness whereof, I, the said Dugald Clerk, have hereunto set my hand
and seal, this Sixteenth day of December, in the year of our Lord One
thousand eight hundred and seventy-nine.
Witness,
EDMUND HUNT,
Patent Agent,
Glasgow.
DUGALD CLERK. (L.S.)