Improvements in Steam Boilers.
Year: 1893

page_text: Date of Application, 19th Jan., 1893
Complete Specification Left, 20th Nov., 1893-Accepted, 13th Jan., 1894
Improvements in Steam Boilers.
We, JOHN HAZELL FRASER, of Millwall Boiler Works Millwall, WILLIAM
WALLINGTON HARRIS, of 43 Regent Square, and A. M. PERKINS & SON
LIMITED, of 43 Regent Square aforesaid, all in the County of London, Engineers,
do hereby declare the nature of this invention to be as follows:-
According to this invention a steam boiler is constructed in such a way that the
furnace gases are made to heat a series of closed het water circulating tubes such
as are used in the Perkins system of hot water heating apparatus and which are set
partly within the boiler and partly within the furnace and serve to convey or
transmit heat from the fire to the water and steam in the boiler by the circulation
of fluid within them-afterwards the furnace gases are led through flues or tubes
passing through the interior of the boiler or through flues along its exterior
so that the gases which still retain considerable heat part with a large proportion
of this heat to the cooler water in the boiler and the gases pass away to the
chimney at no higher temperature than in boilers constructed in the ordinary
ways.
By this means the intense heat generated in the fire box more especially when
the furnace is worked by forced draught will be quickly absorbed and transferred
into the boiler itself and the over-heating of the tube plates and fire box from which
great difficulty now arises will so be prevented. The hot water circulating pipes
are divided into a number of short circulations each having a portion of its length
in the fire and the remainder in the steam and water spaces of the boiler and each
having its own expansion chamber.
By constructing steam boilers in the above way an unusually large quantity of
heating surface can be provided in the fire box and in immediate contact with the
fire and the tubes of which this heating surface is composed being charged with an
independent water or fluid supply that is used over and over again for a long
period will not in any way suffer from internal deposit but will always remain.
clean.
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COMPLETE SPECIFICATION.
Improvements in Steam Boilers.
We, JOHN HAZELL FRASER, of Millwall Boiler Works, Millwall, WILLIAM
WALLINGTON HARRIS, of 43 Regent Square, and A. M. PERKINS & SON
LIMITED, of 43 Regent Square aforesaid, all in the County of London, Engineers,
do hereby declare the nature of this invention and in what manner the same is.

page_text: to be performed to be particularly described and ascertained in and by the following
statement :-
According to this invention a steam boiler is constructed in such a way that the
furnace gases are made to heat a series of closed hot water circulating tubes such
as are used in the Perkins system of hot water heating apparatus and which are set
partly within the boiler and partly within the furnace and serve to convey or
transmit heat from the fire to the water and steam; in the boiler by the circulation
of fluid within them-afterwards the furnace gases. are led through flues or tubes
passing through the interior of the boiler or through flues along its exterior so
that the gases which still retain considerable heat part with a large proportion of
this heat to the water in the boiler and the gases pass away to the chimney at no
higher temperature than in boilers constructed in the ordinary ways.
By this means the intense heat generated in the fire box more, especially when
the furnace is worked by forced draught will be quickly absorbed and transferred,
into the boiler itself and the over-heating of the tube plates and fire box from
which great difficulty now arises will so be. prevented. The hot water circulating;
pipes are divided into a number of short circulations each having a portion of its
length in the fire and the remainder in the steam and water spaces of the boiler and
each having its own expansion chamber.
By constructing steam boilers in the above way an unusually large quantity of
heating surface can be provided in the fire box and in immediate contact with the
fire and the tubes of which this heating surface is composed being charged with an
independent pure water or fluid supply that is used over and over again will not in
any way suffer from internal deposit but will always remain clean.
In the drawings annexed we have shewn examples of steam boilers constructed
to be heated in the manner above described.
Figure 1 is a transverse section and Figure 2 a longitudinal section of a boiler
having two internal furnace flues the sides of which are protected from excessive
heating by hermetically closed circulating heat conveying or "Perkins" tubes a-
across the back end above the bridge are other similar tubes a* between which the
fire gases pass before they enter the smoke box 6 and return to the front through
the tubes c.
As will be seen each tube a ax projects partly into the interior of the
boiler and partly into the furnace flue. The tubes a a* may be carried up high
enough within the boiler for their upper ends to project up into the steam space-
some of them also may be carried up through the top of the outer shell and serve
as stays as shewn or ordinary stays may be used.
Each tube is hermetically closed at its ends and is only partially filled. with
water or other heat carrying fluid so that the upper end of each forms an expansion
chamber as in the circulating heat conveying tubes used in what are known as the
Perkins hot water ovens and for heating buildings.
In Figure 3 three different ways are shewn of securing the tubes to a tube plate.
Figure 4 shews how the ends of the tubes may be secured to the outer shell of a
boiler when the tubes are to be used as stays.
Figures 5, 6, 7 and 8 are cross sections of heat conveying tubes fitted with internal
diaphragms d to assist the circulation within the tube-these diaphragms should be
made to extend from a short distance from the lower end of the tube to above that
part of the tube which is within the fire box.
Figure 9 is a vertical section through the furnace of a horizontal steam boiler.
In this boiler the tubes a project downwards as shewn into the fire chamber and
also into a flue which is below the boiler and extends to the back of the boiler.
The gases from the fire pass along this flue and at the back of the boiler rise
up and return to the front through the tubes c.
Figure 10 is a section of a vertical boiler having hermetically closed circulating
heat conveying tubes a ranged around the sides of the internal fire box and passing,
up through the top of the fire box into the water space of the boiler.
Figure 11 is a section of a similar vertical boiler in which the gases from the

page_text: fire pass from the top, of. the fire box to the chimney outlet through numerous' flue
tubes instead of through a single flue as shown in Figure, 10.
Figures 12 and 13 are cross sections through the upper parts of the boilers shewn
in Figures 10 and 11.
One great advantage of constructing boilers so as to be heated in the above.
described mauner is that as, the fluid in the hermetically closed tubes will always
work at a higher pressure than that in. the boiler itself, and as a consequence will
be kept in more intimate contact with the heated surface of the tube-the tubes-
can be exposed, to a more intense, heat than can boilers worked under ordinary
conditions, where, as so often happens the intense heat generated by a quick or
forced draught, is made to impinge on the tube plate and this intense heat forces
the water away from the plate, and destroys the joint by unequal expansion of the
metal before the heat can be properly absorbed and rendered harmless by the large
mass of the tube surface beyond, the damage taking place before the tube surface
can come properly into play. This action is entirely overcome by the use of the
hermetically closed heat conveying tubes for reducing the temperature of the gases.
before they come into contact with the tube plate or skin of the boiler and yet as
the gases are-subsequently led through the ordinary boiler tubes or along and in.
contact with the shell of the boiler the fire gases will pass away at no higher
temperature than from an ordinary boiler.
A further advantage that these transmitting tubes possess over ordinary boiler
tubes, whether internally or externally heated, is that each tube is 80 .completely
independent of its neighbour, and of the boiler itself, that should it from any cause
become damaged, its loss is confined to itself, the boiler loses the heat conducting
assistance of this single tube, but otherwise suffers no damage either from leakage,.
or any other cause, each tube may in fact be burnt away or broken off in rotation,
and the main structure of the boiler still remain sound. Another feature of
considerable importance in this mode of constructing the heat absorbing surface, is.
that a portion of this surface can be placed in actual contact with the incandescent
fuel, and therefore the absorption can be made to commence from the moment the
fuel is ignited, and thus a portion of the total heat generated can be transmitted by
conduction to the boiler at once, and as the bulk of the heating surface can be made
to interpose between the fire and the shell of the boiler, the temperature of the
heated gases can by this means be reduced to such a degree, that they can do no.
harm to the shell of the boiler or the tube connections, when they finally come in
contact with them.
A further advantage that these tubes possess over ordinary modes of heating,.
is that as the fluid contained in the tubes can be made to work at a much
higher temperature than that of the steam in the boiler, a portion of this tube.
surface can be arranged to occupy the space above the water level and so superheat
or thoroughly dry the steam before it leaves the boiler, a most important matter as
affecting the economical efficiency of the engine.
Having now particularly described and ascertained the nature of our said inven--
tion and in what manner the same is to be performed we declare that what we
claim is: :-
1. A steam boiler constructed in such a way that the fire and furnace gases are
made to heat a series of hermetically closed fluid circulating tubes which are set
partly within the boiler and partly within the boiler furnace and serve to convey
heat from the fire to the water and steam in the boiler by the circulation of fluid
within them, in such a way that the furnace gases are afterwards led through flues
or tubes passing through the interior of the boiler or are led through flues so as to
be brought into contact with the exterior of the boiler substantially as described.
2. A steam boiler with internal furnace flue or fire box and a series of
hermetically closed fluid circulating tubes which are set partly within the interior
of the boiler and partly within the fire box to protect its sides from excessive
heating substantially as described.

page_text: 3. The construction of steam boilers substantially as herein before described and
illustrated in the drawing annexed.
Dated this 20th day of November 1893
.
J. H. FRASER,
W. W. HARRIS,
A. M. PERKINS & SON, LIMITED,
By Carpmael & Co.,
Agents for the Applicants.