IMPROVEMENTS IN STEAM GENERATORS
Year: 1866

page_text: LETTERS PATENT to William Alexander Lyttle, Officer of the Secretary's
Department, General Post Office, London, for the Invention of
"IMPROVEMENTS IN STEAM GENERATORS."
Sealed the 3rd May 1867, and dated the 15th November 1866.
PROVISIONAL SPECIFICATION left by the said William Alexander Lyttle
at the Office of the Commissioners of Patents, with his Petition, on the
15th November 1866..
I, WILLIAM ALEXANDER LYTTLE, Officer of the Secretary's Department,
General Post Officé, London, do hereby declare; the nature of the said
Invention for "IMPROVEMENTS IN STEAM GENERATORS," to be as follows:-
I render the furnace and ash-pit of a steam generator air-tight by means of
a metal casing wherever needed, together with close fitting fire and ash, doors,
and I supply the fire with air by means of a suitable blowing apparatus,' such
as a centrifugal or other air pump, provision, being made by branch supply
pipes (adapted with cocks or valves), one above the fire and one underneath
it for regulating the perfect.combustion of the solid and gaseous portions of
the fuel, with or without a steam jet in the ash-pit. In the next place I
cause the cold air to be either sucked or propelled through an air-heating
apparatus inside or connected with the chimney, and constructed like any of
the steam superheaters or vapour coolers now in use, so that the air may
become heated on its way through it to the fire by absorbing the heat of the
smoke or waste gases, which should move though this air heater in an opposite

page_text: direction. This hot blast arrangement, which I shall call a "smoke filter,"
may, for instance, consist of an inner concentric metallic lining of the funnel
or chimney of such dimensions that while there is sufficient room for the
passage of the smoke in the present ordinary way by a free draught up its
inside there is also sufficient space between it and the outer shell of the
chimney to admit of the downward passage of cold air to the fire under the
action of the above-mentioned blowing apparatus. Again, the arrangement
for heating the blast may consist of a number of vertical tubes placed as a
lining around the interior surface of the chimney, and connected jointly at one
end with the blowing apparatus and at the other end with the fire.
Another arrangement of the smoke filter would be that of a second funnel,
formed precisely like a multitubular boiler placed on end with its bottom
exteriorly to its tube plate communicating with the smoke passage at the
base of the ordinary or free draught chimney. When the latter chimney is
"shut by a throttle or other suitable valve actuated by the fireman the smoke
gases become thereby "shunted" or diverted into the tubes of the second or
multitubular chimney to become filtered of their heat there in transit up the
tubes. The cold air entering one end of the smoke filter, like the feed water
of a steam boiler, circulates around those tubes and absorbs their heat on its
passage to the furnace. The smoke may first be passed through a superheater
of steam of any desired form. The ordinary or free draught chimney may be
placed in the axis of the multitubular funnel; or these two smoke passages,
whatever may be the form of structure of the smoke filter, may bear any other
desired relations to each other as regards position. The second funnel or
smoke filter need not necessarily be vertical, nor yet of the same magnitude as
the free draught funnel; if made very short or placed horizontally it may be
found necessary to connect it with the free draught funnel at both ends, so
that when the herein-before mentioned throttle or other valve is closed against
the free draught the smoke gas may pass through the multitubular or other
smoke filter and then re-enter the free draught funnel above the throttle or
other valve which closes its bottom.
In order to work a steam generator constructed on this plan it will first be
necessary to light the fire with a free draught of air, as at present, by opening
the furnace doors and the throttle or other valve in the free draught chimney.
When steam is thus got up the blowing apparatus, worked either directly by
a separate auxiliary engine or in any other desired way, is then brought into
action, the free draught passages being all first closed so far as may be found
necessary. Part of the space above described as requisite for the passage of
the cold air in the smoke filter might with advantage be set aside for heating

page_text: the feed water of the boiler, and the vapour of the water so heated may be
prevented intermixing with the heated air of the blast, if found objectionable,
by entirely separating the air from the water.
In the case of the locomotive
the smoke filter can if desired be placed horizontally along one or both
sides of the boiler; thus in the event of the above-mentioned multitubular
arrangement being employed the smoke tubes would open from the top of
the smoke box on-one side, and the smoke gases entering these would pass
along this horizontal funnel on that side, then cross the boiler by an outside
connecting pipe, and entering the. tubes of a second similar horizontal
funnel they would return to the smoke box end of the boiler and there
enter the free draught chimney at a point above the before-mentioned
throttle or other valve. A throttle valve may also be placed in such a
position as to restrict to any desired extent in any kind of engine the rate.
of egress of the smoke when passing through the smoke filter, and by this
means any desired degree of pressure can be got up in the furnace and
steadily maintained; this would have the effect of trapping back the flame,
and by retarding its run along the tubes or flues of the boiler it would so
cause the flame to radiate into the boiler a larger proportion of its heat before
entering the smoke filter or funnel. This compression of the blast would be
especially serviceable in the combustion of liquid fuel by ensuring the perfect
combustion of the flame: before it becomes extinguished in the smoke filter.
In burning liquid or gaseous fuel, however, I would recommend that in order
to give. a long run to the flame the boiler should be provided with a staple
tube or a return flue of diameter wide enough to allow of the full combustion
of the flame when passing through it; the flame or smoke gases might then
be allowed to enter the horizontal boiler tubes, as at present, on their way to
the smoke filter or funnel.
In the use of liquid fuel with this steam generator it may be found desirable
to adopt a modification of the apparatus now known amongst perfumers under.
the name of the "atomiser," which consists of two glass tubes placed at right
angles, so that a blast of air through one tube rushes across the end of the
other, and by thus causing a vacuum in the latter draws up and scatters in
the form of a fine vapour any liquid in which the vacuum tube may be
immersed. By thus arranging a number of vacuum tubes in the blast of the
blowing apparatus of my steam generator it is evident that coal oil or other
liquid fuel may be comminuated or vapourised and so burnt in the furnace
in admixture with the supply of air, and with or without the presence of
solid fuel.
Another plan of burning liquid fuel in a steam generator, constructed

page_text: according to this Patent, is to scatter the liquid fuel in a finely divided shower
over a well-lighted fire of solid fuel, keeping up the supply by means of a feed
pump like that used for feeding the boiler with water. When both ends of
the smoke filter, are covered one or both should be provided with a removable
cap, in order that access may be had readily to the smoke passages for the
removal of any obstruction. When steam mixed with smoke-gases passes
through the smoke filter provision will of course have to be made for the
escape of the water condensed in the smoke filter, so as to prevent its running
backward into the fire. Amongst other simple and obvious plans for such a
purpose I may mention that of an inverted syphon, like the manoineter
steam guage, which can be screwed into the part into which the water con-
densed in the smoke filter will gravitate. If the length of the arms of this
syphon are made proportional to the strength of the blast it is evident that the
water will always overflow from it without the escape of the smoke. A simple
slit or vent pipe however may be found sufficient for the purpose where the
pressure of the blast is low. In closing the furnace to prevent the backward
escape of the flame there can be either a single door covering both ash-pit
and furnace, or there can be a separate door for each; or, again, there can be
two doors for those parts of the furnace fixed immovably to one vertical axis,
and thus opening and shutting together. In some instances, however, it may
be found necessary to use an outside metallic casing in front of the fire-door
and ash-pit and fitted with a fire-door and ash-door, so that the inner fire-door
by intercepting the heat may preserve the outer fire-door from warping.
Having now described the nature of my Invention, and some of the best
means with which I am acquainted for carrying it into effect, I wish it to be
understood that I in no way limit myself to the precise details of the arrange-
ments herein-before specified, as they may obviously be variously modified
without departing from the nature of my Invention; but what I claim
is,―
First, so constructing steam generators for any purposes that at one time
their fuel shall be burnt with a blast heated by the waste heat of the smoke,
or smoke and steam, and with or without special increase of its pressure by
throttling, as herein-before described, whilst at another time the air can be
supplied to the furnace and the products of combustion allowed to pass into
the chimney by means of a draught produced in the ordinary manner.
Second, I claim for the use of steam generators constructed in accordance
with this Specification the several novel details herein-before described.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Alexander Lyttle in the Great Seal Patent Office on
the 14th May 1867.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
ALEXANDER LITTLE, Officer of the Secretary's Department, General Post
Office, London, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fifteenth day of November, in the year of our
Lord One thousand eight hundred and sixty-six, in the thirtieth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said William Alexander Lyttle, Her special licence that I, the said
William Alexander Lyttle, my executors, administrators, and assigns, or such
others as I, the said William Alexander Lyttle, my executors, administrators,
and assigns, should at any time agree with, and no others, from time to time
and at all times thereafter during the term therein expressed, should and
lawfully might make, use, exercise, and vend, within the United Kingdom of
Great Britain and Ireland, the Channel Islands, and Isle of Man, an Inven-
tion for "IMPROVEments in Steam GENERATORS," upon the condition (amongst
others) that I, the. said William Alexander Lyttle, my executors or admi-
nistrators, by an instrument in writing under my, or their, or one of their
hands and seals, should particularly describe and ascertain the nature of the
said Invention, and in what manner the same was to be performed, and
cause the same to be filed in the Great Seal Patent Office within six
calendar months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said William Alexander Lyttle, do hereby
declare the nature of my said Invention, and in what manner the same is
to be performed, to be particularly described and ascertained in and by the
following statement :-
I render the furnace and ash-pit of a steam generator air-tight by means of
a metal or other casing wherever needed, together with close fitting fire and
ash doors, and I supply the fire with air by means of a suitable blowing
apparatus, such as a centrifugal or other air pump, provision being made by
branch supply pipes (adapted with cocks or valves), one above the fire and
one underneath it, for regulating the perfect combustion of the solid and
gaseous portions of the fuel, with or without a steam jet in the ash-pit. In the
next place I cause the cold air to be (according to the position of the blowing
apparatus) either sucked or propelled through an air-heating apparatus inside

page_text: or connected with the chimney, and constructed like any of the steam super-
heaters or vapour coolers now in use, so that the air may become heated on
its way through it to the fire by absorbing the heat of the smoke or waste
gases, which should move through this air heater in an opposite direction.
This hot blast arrangement may, for instance; consist of an inner concentric
metallic lining of the funnel or chimney of such dimensions that while there
is sufficient room for the passage of the smoke in the present ordinary way by
a free draught up its inside, there is also sufficient space between it and the
outer shell of the chimney to admit of the downward passage of cold air to
the fire under the action of the above-mentioned blowing or exhausting
apparatus. Again, the arrangement for heating the blast may consist of a
number of vertical tubes placed as a lining around the interior surface of the
chimney, and connected jointly at one end with the blowing apparatus and at
the other end with the fire. Another arrangement of the air-heater would. be
that of a second funnel formed precisely like a multitubular boiler placed on
end with its bottom exteriorly to its tube plate communicating with the smokė
passage at the base of the ordinary or free draught chimney. When the
latter chimney is shut by a throttle or other suitable valve; actuated by the
fireman, the smoke gases become thereby "shunted" or diverted into the tubes
of the second or multitubular chinney to become filtered of their heat there
in transit up the tubes. The cold air entering one end of the air heater, like
the feed water of a steam boiler, circulates around those tubes and absorbs
their beat on its passage to the furnace. The smoke may first be passed
through a superheater of steam of any desired form. The ordinary or free
draught chimney may be placed in the axis of the multitubular funnel, or these
two smoke passages, whatever may be the form of structure of the air heater,
may bear any
other desired relations to each other as regards position. In
the case of stationary engines the outer shell of the air heater may of course
be formed of brickwork. The second funnel or air heater need not necessarily
be vertical nor yet of the same magnitude as the free draught funnel; if
made very short, or placed horizontally, it may be found necessary to connect
it with the free draught funnel at both ends, so that when the herein-before
mentioned throttle or other valve is closed against the free draught the smoke
gas may pass through the multitubular or other air heater and then re-enter
the free draught funnel above the throttle or other valve which closes its
bottom. The smoke gas may however be thrown off by a separate flue, and
when the hot blast to the fire is produced by the action of an exhaust fan, the
best position for the latter will be at the outlet extremity of any air heater or
system of air heaters which may be used.

page_text: In order to work a steam generator constructed on this plan it will first be
necessary to light the fire with a free draught of air, as, at present, by opening
the furnace doors and the throttle or other valve in the free draught chimney.
When steam is thus got up the blowing apparatus (worked either directly by
a separate auxiliary engine, or in any other desired way) is then brought into
action, the free draught passages being all first closed so far as may be found
necessary. Part of the space above described as requisite for the passage of
the cold air in the air heater might with advantage be set aside for heating the
feed water of the boiler, and the vapour of the water so heated may be pre-
vented intermixing with the heated air of the blast, if found objectionable, by
entirely separating the air from the water. In the case of the locomotive the
air heater can, if desired, be placed horizontally along one or both sides of the
boiler; thus in the event of the above-mentioned multitubular arrangement
being employed the smoke tubes would open from the top of the smoke box
on one side, and the smoke gases entering these would pass along this
horizontal funnel on that side, then cross the boiler by an outside connecting
pipe, and entering the tubes of a second similar horizontal funnel they would
return to the smoke box end of the boiler, and there enter the free draught
chimney at a point above the before-mentioned throttle or other valve. A.
throttle valve may also be placed in such a position as to restrict to any desired
extent in any kind of engine the rate of egress of the smoke when passing
by propulsion through the air heater, and by this means any desired degree of
pressure can be got up in the furnace and steadily maintained; this would
have the effect of trapping back the flame, and by retarding its run along the
tubes or Blues of the boiler it would so cause the flame to radiate into the
boiler a larger proportion of its heat before. entering the air heater or funnel.
This compression of the blast would be especially serviceable in the com-
bustion of liquid fuel by ensuring the perfect combustion of the flame before it
becomes extinguished in the air heater. In burning liquid or gaseous fuel, how-
ever, I would recommend that in order to give a long run to the flame the boiler
should be provided with a staple tube or a return flue of diameter wide
enough to allow of the full combustion of the flame when passing through it;
the flame or waste gases of combustion might then be allowed to enter the
horizontal boiler tubes, as at present, on their way to the air heater or funnel.
In the use of liquid. fuel with this steam generator it may be found
desirable to adopt a modification of the apparatus now known amongst
perfumers under the name of the "atomizer," which consists of two glass
tubes placed at right angles, so that a blast of air through one tube rushes
across the end of the other, and by thus causing a vacuum in the latter draws

page_text: up and scatters in the form of a fine vapour any liquid in which the vacuum
tube may be immersed. By thus arranging a number of vacuum tubes in the
blast of the blowing apparatus of my steam generator when the air is pro-
pelled into the fire instead of exhausted from the flue, it is evident that coal
oil or other liquid fuel may be comminuated or vapourized and so burnt in the
furnace in admixture with the supply of air, and with or without the presence
of solid fuel. When, however, the draught is caused by, an exhaust. fan there
may be an auxiliary blast of greater strength, with or without admixture of
steam, for the dispersion as spray of the liquid fuel, or a jet of steam only may
be used for the latter purpose.
Another plan of burning liquid fuel in a steam generator constructed
according to this Patent is, to scatter the liquid fuel in a finely, divided shower
over a well-lighted fire of solid fuel, keeping up the supply by means of a feed
pump like that used for feeding the boiler with water. When both ends of
the air heater are covered one or both should be provided with a removable
cap or lid, in order that access may be had readily to the smoke passages for
the removal of any obstruction. When steam mixed with smoke gases passes
through the air heater provision will of course have to be made for the escape
of the water condensed in the air heater so as to prevent its running backward
into the fire. Amongst other simple and obvious plans for such a purpose I
may mention that of an inverted syphon, like the manometer steam guage which
can be screwed into the part into which the water condensed in the air heater
will gravitate. If the length of the arms of this syphon are made proportional
to the strength of the blast it is evident that the water will always overflow
from it without the escape of the smoke or the entrance of cold air when the
blast is caused by an exhaust fan. A simple slit or vent pipe may, however,
be found sufficient for the purpose when the pressure of the blast is low. In
closing the furnace to prevent the backward escape of the flame or the direct
entrance of cold air, according as the air is sucked or propelled, there can be
either a single door covering both ash-pit and furnace, or there can be a
separate door for each; or, again, there can be two doors for those parts of
the furnace fixed immovably to.one vertical axis, and thus opening and shutting
together. In some instances, however, it may be found necessary to use an
outside metallic casing in front of the fire-door and ash-pit and fitted with a
fire-door and ash-door, so that the inner fire-door by intercepting the heat may
preserve the outer fire-door from warping.
г
Having now described the nature of my Invention, and some of the best
means with which I am acquainted for carrying it into effect, I wish it to
be understood that I in no way limit myself to the precise details of the

page_text: arrangements herein-before specified, as they may obviously be variously
modified without departing from the nature of my Invention; but what I
claim is,
Firstly, so constructing steam generators for any purposes that at one time
their fuel shall be burnt with a blast (caused by propulsion or suction of the
air) heated by the waste heat of the smoke, or smoke and steam, and with or
without special increase of its pressure by throttling when propelled, as
herein-before described, whilst at another time the air can be supplied to the
furnace and the products of combustion allowed to pass into the chimney by
means of a draught produced in the ordinary manner.
Secondly, I claim for the use of steam generators constructed in accordance
with this Specification the several novel details herein-before described.
In witness whereof, I, the said William Alexander Lyttle, have here-
unto set my hand and seal, this Fourteenth day of May, One thousand
eight hundred and sixty-seven.