Improvements in and relating to Steam Generators.
Year: 1892

page_text: Date of Application, 26th Oct., 1892
Complete Specification Left, 25th July, 1893-Accepted, 26th Aug., 1893
PROVISIONAL SPECIFICATION.
Improvements in and relating to Steam Generators.
I, HIRAM STEVENS MAXIM, of Baldwyn's Park, Bexley, in the County of
Kent, Mechanical Engineer, do hereby declare the nature of this invention to be.
as follows:-
:-
This invention relates to steam generators having a large number of very small.
water tubes through which the water flows in a comparatively steady stream and is
therein converted into steam. In such tubes there is no room for convection
currents such as are experienced in ordinary types of boilers.
My improved steam generator is constructed by preference with two feed pipes
near the base which pipes are connected with two steam and water drums by a
large number of very small tubes made preferably.of
The said tubes are
copper.
bent into wavy forms to increase the heating surface, and are arranged to cross
each other over the furnace, the tubes at each intersection being tied together by
asbestos cord. This construction gives ample support to the tubes. The said
two steam and water drums are connected by other similar small tubes with a
central steam drum which also contains some water from which drum the steam is
taken by any suitable arrangement of steam pipe, a convenient form of such pipe
being one that has a slit in the bottom thereof extending the whole length of that
part of the pipe which is in the steam drum. Some of the small tubes which
connect the steam and water separating drums with the central steam drum are
arranged to project some distance into the said separating drums for a purpose
hereinafter described, and the said drums are preferably provided each with a
longitudinal rib to better separate the incoming and outgoing fluid. 1 prefer to
connect the small generating tubes to the feed pipes and to the drums above
mentioned by means of a union such as that described in the Specification of my
prior Patent No. 19228 dated 6th November 1891 with reference to Figure 19 of
said Specification.
The feed water which is supplied at a constant pressure higher than that in the
generator notwithstanding any variableness in the quantity required is first heated
in a feed water heater arranged in the upper part of the boiler and is then delivered
through an adjustable nozzle into a vertical pipe which is in communication with
the steam drum, the steam and water separating drums, and the water pipes afore-
mentioned in the base of the generator. A forced circulation is thereby maintained
through the generator. The said injector nozzle is preferably constructed similar
to that described with reference to Figure 17A of the Specification above mentioned
No. 19228 A.D. 1891.
The
The generator is enclosed in a suitable casing which may be lined or covered or
both lined and covered with asbestos or other suitable non-conductor of heat.
casing is provided with a chimney.
The generator is heated by burning gaseous fuel thereunder, the vapour of
paraffin, naphtha, or kerosene oil being preferred. For vapourizing the said oi! I
provide a small vapourizer which I support by a spring or springs and connect the
same to the valve which controls the admission of oil thereinto in such manner that
when the vessel is over supplied with oil its weight depresses the supporting spring
or springs and thereby partially closes the admission valve and reduces the supply;
and on the other hand when there is a scarcity of oil in the vessel its increased
buoyancy operates to open the admission valve and admit more oil thereinto. The
oil is supplied by a pump at a pressure superior to the pressure required in the
vapourizer. In this manner I maintain a fairly constant level of oil in the vapourizer.
The heat required to vapourize the oil is obtained by burping a portion of the

page_text: vapour in a burner underneath the vapourizer. The supply of vapour for this
purpose is controlled by a valve the seat of which is formed in one end of the
vapourizer and the valve proper of which is secured to the other end of the
vapourizer, said ends being made flexible so that when the pressure in the vessel
increases, the ends are forced out and partially close the valve thus reducing the
supply of vapour to the burner, and vice versa when the pressure in the vapourizer
diminishes, the valve is opened by the contraction of the flexible ends and more
vapour is supplied to the burner. The pressure of vapour is thus maintained
approximately constant.
Within the steam drum of the generator is placed a pipe which is in communi-
cation with a series of tubes arranged immediately over the furnace, the said pipe
and tubes forming a closed system which is partially filled with water. A small
branch pipe leading from a convenient part of the said system communicates with
one side of a diaphragm valve which controls the flow of vapour from the
vapourizer to the main burner or furnace of the steam generator, the flow being
thereby regulated by the pressure of steam in the closed system just described
which pressure is higher than that in the generator. The action of this apparatus
is as follows: Should there be too much water delivered to the generator thus
filling the side steam and water drums, some of the water is immediately carried
over into the steam drum by the projecting or dipping tubes aforementioned and
cools the pipe therein which forms part of the closed system. A portion of the
steam in said system is thus condensed and the pressure reduced which has the
effect of opening the vapour regulating valve and thus increasing the vigour of
the fire. The pressure in the generator is thereby very soon raised sufficiently to
check the influx of water and thus reduce the quantity of the same in the steam
and water drums to the normal amount. In the same manner any lack of water
causes the pressure to increase in the closed system and thereby shut down the fire
and reduce the pressure in the generator, thus inducing more water to flow therein.
I prefer to arrange a small steam pump to feed the water into the generator and
the oil to the vapourizer in such manner that the pressure of the water will be in
excess of the steam pressure when the valve is wide open so that whenever the
water pressure is relieved, the steam pump will start automatically. The oil pump
is provided with a relief valve so that the excess of oil passes back into the supply
tank from whence it was pumped. I sometimes provide a regulating valve in the
steam pipe leading to the pump, said valve being controlled by the water pressure.
The generator is thus automatic in its action the vigour of the fire being pro-
portioned always to the requirements. Little attention is required, and it is only
necessary to open the steam valve in order to bring a very intense fire instantly
into action.
Dated this 28th day of October 1800
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in and relating to Steam Generators.
I, HIRAM STEVENS MAXIM, of Baldwyn's Park, Bexley, in the County of
Kent, Mechanical Engineer, do hereby declare the nature of this invention
and 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 steam generators having a large number of very small
water tubes through which the water flows in a comparatively steady stream and is
therein converted into steam. In such tubes there is no room for convection
currents such as are experienced in ordinary types of boilers.
:
My said invention comprises the improvements hereinafter described.

page_text: In the accompanying drawings,
Figure 1 is a longitudinal central section of a steam generator constructed.
according to my invention.
Figure 2 is a transverse section of the same.
Figure 3 is a rear end view of the same partly in section, and
Figure 4 is a front end view, the oil vaporizer hereinafter described being shown
in section.
Figure 5 is a central longitudinal section drawn to a larger scale of a regulating
valve for controlling the supply of steam to the feed pump.
Figure 5 is a similar section showing a modified form of such regulating valve.
Figure 6 is a central longitudinal section also drawn to a larger scale of a.
regulating valve for controlling the supply of gas or oil vapour to the burner.
Figure 7 is a side elevation of the same.
Figure 8 is a section taken on the line a Figure 6.
Figure 9 is a section taken on the line y y Figure 7.
Figure 9 is a view of a detail.
Figure 10 is a sectional plan on the line
Figure 7.
Figure 11 is a longitudinal section of one of the drums hereinafter described.
Figure 12 illustrates in enlarged section a union hereinafter referred to.
Like letters of reference denote corresponding parts throughout the drawings.
My improved steam generator is constructed by preference with two feed
pipes A, A near the base which pipes are connected with two steam and water
drums B, B by a large number of very small tubes C made preferably of copper.
The said tubes are bent into wavy forms to increase the heating surface and are
arranged to cross each other over the fire, the tubes at each intersection being tied
together preferably by asbestos cord. This construction gives ample support to the
tubes. The said two steam and water drums B B are connected by other small
tubes C with a central steam drum D which also contains some water. From said.
drum D the steam is withdrawn by any suitably constructed steam pipe E, a.
convenient form of such pipe being one that has a slit or opening E' in the bottom.
thereof extending the whole length of that part of the pipe which is in the steam.
drum. Some of the small tubes C' are arranged to project some distance into the
steam and water separating drums B, B as shown with reference to Figures 2 and 11.
for a purpose hereinafter described, and the said drums are preferably provided.
each with a longitudiual rib B' to better separate the incoming and outgoing fluid..
That is to say, the steam enters the drum B on one side the partition B and flows
out on the other side of said partition. I prefer to connect the small generating
tubes C to the feed pipes A, A and to the drums B, B by means of unions such as.
are described in the Specification of my prior Patent No. 19228 dated 6th November
1891 with reference to Figure 19 of said Specification. A greatly enlarged sectional.
view of one of such unions is shown in Figure 12 herewith.
The feed water which is supplied at a constant pressure higher than that in the
generator, notwithstanding any variableness in the quantity required, is first heated
in a feed-water heater arranged and suitably supported in the upper part of the
boiler. Said feed-water heater may advantageously consist of a pair of pipes F
joined by small tubes F. The water is delivered into one of said pipes and passes.
thence through the small tubes F into the other of said pipes whence it is.
delivered along a pipe F2 and through an adjustable nozzle F, see Figure 3, into a.
vertical pipe G. Said pipe & communicates with the steam drum D by a branch G¹,.
with the steam and water separating drums B, B, by branches G2, G, and with the
feed pipes A, A in the base of the generator by branches G³, G³. By this con-
struction, a forced circulation is maintained through the generator. The said
injector nozzle F³ is preferably constructed similarly to that described with reference.
to Figure 17A of the Specification above mentioned No. 19228 A.D. 1891.
The generator is enclosed in a suitable casing H which may be lined or covered.
or both lined and covered with asbestos or other suitable non-conductor of heat.
The casing is provided with a chimney H'.

page_text: The generator is heated by gaseous fuel which is burned thereunder, the vapour
of paraffin, naphtha, or kerosene oil being preferred. For vaporizing the oil I
provide a small apparatus J which I support by a spring J' carried by a bracket J2.
suitably connect the said apparatus J to the handle or lever K¹ of the valve K
which controls the admission of oil into the vaporizer. Such connection may be
effected by means of a spindle J³ the whole operating in such manner that when
the vessel is over-supplied with oil its weight compresses the supporting spring J
and thereby partially closes the admission valve K and reduces the supply; and on
the other hand when there is a scarcity of oil in the vessel J the latter is raised by
the spring and thus opens the admission valve K and admits more oil into the
vaporizer. In this manner I maintain a fairly constant level of oil in the vaporizer.
The oil is supplied by a pump at a pressure superior to the pressure required in the.
vaporizer. The heat required to vaporize the oil is obtained by burning a portion
of the oil vapour in a burner M placed underneath the vaporizer in a chamber
formed between a dished end plate Js forming the lower end of the reservoir and
the lower end plate J8 of the vaporizer J. The supply of vapour for this purpose
is controlled by a valve L the seat L¹ of which is formed in the flat end J* of the
vaporizer. The valve L is secured by a tubular stem L² to the other end J' of
the vaporizer. Said tubular stem L2 is open at its upper end and closed at its
lower end.
L³ is a pipe for conducting, the vapour from the tubular stem L² to the burner M.
The ends J, J of the vaporizer are flexible so that when the pressure in the
vessel increases, the said ends are forced outward and partially close the valve thus
reducing the supply of vapour to the burner, and vice versa when the pressure in
the vaporizer diminishes the valve is opened by the contraction of the flexible ends.
and more vapour is supplied to the burner.. The pressure of vapour is thus
maintained approximately constant. The products of combustion from the
burner M pass up through tubes J secured in the upper and lower end plates of
the vaporizer, and make their exit by the chimney J.
Within the steam drum D of the generator is placed a pipe N which is in com-
munication through vertical pipes N₁ and cross-pipes N2 with a series of tubes N³
arranged immediately over the furnace, the said pipes and tubes forming a closed.
system which is partially filled with water. A small branch pipe N leading from.
a convenient part of the said system communicates with an equilibrium valve O
hereinafter described which controls the flow of vapour from the vaporizer to the
main burner P of the steam generator, the flow being thereby regulated by the
pressure of steam in the closed system just described which pressure is higher than
that in the generator. The oil vapour coming from the vaporizer J passes along
a pipe Q to the equilibrium valve O and thence by a pipe Q¹to the main burner P.
Many forms of equilibrium valves might be made to serve the required purpose.
One form which I have devised and which I find very suitable is that illustrated in
Figures 6 to 10: o is the valve casing to which are secured the gas or vapour inlet
and outlet pipes Q, Q. o¹ is the valve proper which is of the double beat pattern
and the spindle of which is suitably guided at top and bottom. o² is a stuffing-box
through which the valve spindle passes, the packing being kept tight by a spring
03
which bears on the top of the valve. o is a tube mounted. on the valve casing lid;
o is a small fitting secured in the top end of the tube o' and adapted to receive a
long piston or ram of which is suitably packed to prevent leakage.
Said piston is
connected by a rod o' to the valve spindle and is supported by a spring of which
rests on a piece of adapted to slide up and down in the tube o. Said piece o is
connected with a pair of side levers p by radial screw pins p³ which pass through
longitudinal slots o⁰ in the side of the tube. Said levers p are connected together
at their ends and are joined at one end by a link p² to a pair of bars or plates p³
secured to the valve-casing lid. p is a screw that works through a nut p mounted
in the other end of the levers p. The lower end of the screw p is adapted to turn
but not slide in a socket provided in the connecting piece po see Figures 9 and 9 of
the corresponding end of the side plates p³. When the screw is rotated by

page_text: means of its crank handle p' the ends of the levers p are raised or lowered and the
compression of the spring of is thereby increased or diminished. The open upper
end of the fitting o³ is adapted to be connected to the steam pipe N Figure 4 so
that the pressure of steam in said pipe, that is to say, in the closed system before
described is free to act on the piston of thereby compressing the spring of and
tending to close the valve o'. The pressure required to close the valve for any
position of the levers p is indicated by a pointer p8 secured to or formed on the end
of one of said levers and which moves over. a scale p' fixed to one of the bars or
plates p³ when the levers are adjusted.
A bye-pass q is provided in the valve which bye-pass can be opened and closed
by a screw-down valve 7 operated by a crank-handle q².
The regulating valve shown at O Figure 4 is constructed differently from that
just described, but it acts in a precisely similar manner.
The action of this apparatus is as follows: Should there be too much water
delivered to the generator thus filling the drums B, B, some of such water is
immediately carried over into the steam drum D by the projecting or dipping
tubes C aforementioned and cools the pipe N therein which forms part of the
closed system before described. A portion of the steam in said system is thereby
condensed and the pressure reduced, which has the effect of opening wider the
vapour-regulating valve O thus increasing the fire. The pressure in the generator
is thereby very soon raised sufficiently to check the influx of water and thus
reduce the quantity of the same in the drums B, B to the normal amount. In a
like manner any lack of water in the generator causes the pressure to increase in
the closed system N, N', N2, N3 and thereby shut down the fire and reduce the
pressure in the generator, thus inducing more water to flow there into.
2"
The water is fed to the generator and the oil to the vaporizer by means of a
small steam pump.
In the steam pipe of said pump there is arranged a regulating
valve to automatically control the supply of steam to the pump according to the
pressure that exists in the boiler.
One construction of regulating valve made in
accordance with this part of my invention as shown by Figure 5 comprises a
casing having an inlet for steam at 1, an outlet for steam at 2, and a contracted
part at forming a valve seat between said inlet and outlet. is a piston which
fits and can slide axially in the casing and is. rigidly connected. by a spindle b
with a valve which is adapted to bed on the aforesaid valve seat and close the
passage for steam through the casing. is a strong spring compressed between
the piston and the adjoining end of the casing which is removable and is
furnished with a hole to prevent compression behind the piston. The said
spring tends to push the valve open while the steam pressure in the casing
acting on the piston tends to close the valve, and these opposing forces in practice
operate to maintain the valve fairly steady about one position with a slight movement
on either side of said position. Any sudden increase of steam pressure checks the
pump and any sudden decrease causes the pump to work a little faster.
In a modified form of regulating valve constructed as shown in Figure 5 the
apparatus is fitted with a cup leather s in lieu of an ordinary piston, and said cup-
leather is exposed to the pressure of the water in the generator through the inlet
pipes which connects preferably with one of the lower pipes A of the generator.
is the steam inlet, the steam outlet, and the regulating valve proper
corresponding with the parts marked with the same letters in the regulating valve
shown in Figure 5. The cup-leather is backed by a spring and is rigidly
connected to the valve by a rod which in this case works through a stuffing.
box. The water pressure acting on the cup-leather compresses the spring
and tends to close the valve thus controlling the flow of steam to the pump in
accordance with the pressure in the boiler.
It will be seen that the generator is automatic in its action, the fire being
proportioned always to the requirements. Little attention is required, and it is
only necessary to open the steam valve in order to bring a very intense fire
instantly into action.

page_text: '
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is
1. A self-regulating steam generator heated by gaseous fuel, so constructed that
the flow of water thereinto operates to control the fire in such a manner that any
excess of water increases the fire and any lack of water reduces the fire, for the
purpose specified.
2. The combination, with such a steam generator, of a steam pump for feeding
the water to the generator and oil to the vaporizer so constructed and arranged
that it begins to work when the pressure in the generator falls below a certain
predetermined limit, and stops when it rises above said limit, for the purpose
specified.
3. A steam generator comprising a pipe or pipes to be filled with water,
intermediate drums for containing steam and water and connected with the said
pipe or pipes by very small evaporating tubes, and a steam drum connected with
the steam and water drums by other very small evaporating tubes, said steam
drum being furnished with a return pipe connecting with the first named pipe or
pipes and with the steam and water drums, for the purpose specified.
4. In the said steam generator, projecting the ends of some of the small
evaporating tubes C₁ into the steam aud water drums B, substantially as described,.
for the purpose specified.
5. The combination, with the steam and water drums B, and the evaporating
tubes C and C¹, of the longitudinal dividing ribs B' in said drums, substantially
as described, for the purpose specified.
6. A vaporizer, for supplying a steam.generator with gaseous fuel, mounted on
a yielding or spring support and connected with the handle or lever of the oil
supply-valve in such a manner that the variations in the weight of the vaporizer
consequent upon the changes in the quantity of oil contained therein operate to
regulate the supply of oil thereto, for the purpose specified.
7. The means for controlling, in accordance with the pressure in the vaporizer,
the supply of vapour to the burner used for vaporizing the oil, substantially as
described.
8. An oil vaporizer constructed substantially as described with reference to the
drawings, and operating as, and for the purpose, specified.
9. The combination, with the steam generator hereinabove described, of the
regulating valve constructed substantially as described with reference to
Figures 6 to 10 of the drawings; for the purpose specified.
10. The regulating valve constructed substantially as described with reference
to Figure 5 or to Figure 5 and operating as, and for the purpose, specified.
11. A steam generator constructed substantially as described with reference to
the accompanying drawings, and operating as specified.
Dated this 25th day of July 1893.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.