Improvements in Steam Generators.
Year: 1897

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Improvements in Steam Generators.
I, RICHARD HEBER RADFORD, 15, St. James' Row, Sheffield, in the County of York,
Mechanical Engineer, do hereby declare the nature of my said invention to be as
follows:-
The objects of my invention are to construct a steam generator specially adapted
for either a high or low rate of steaming, also to reduce the weight and space occupied
in proportion to the power generated.
My invention is applicable to a great variety of steam generators, but is more
particularly applicable for use in a marine type of boiler, as for example, for torpedo
and despatch boats and other ships of war and the like, in which the demand for
steam is sometimes sudden and urgent and the rates of steaming subject to
considerable variations.
I construct my improved steam generator so that it can be used either with
natural or with forced draught and with either natural or forced circulation, thus,
when a low or moderate rate of steaming is required natural draught with either
natural or forced circulation may be employed, and where a higher or express rate of
steaming is required both forced draught and forced circulation will be employed as
circumstances may require.
I effect this, firstly, by providing a number of high pressure water jets so arranged
and distributed inside the generator in the vicinity of the most effective heating
surface, that when the heat is intensified to a degree sufficient to cause overheating
of the plates, water may be injected so as to impinge on the back of the plates with a
sufficient force to break up or prevent the harmful formation of spheroidal steam and
consequent overheating, thereby enabling a much greater draught to be employed.
This part of my invention is applicable to a great number of existing types of steam
generators, and would enable many such to employ much greater draught and work
to a much higher rate of steaming than is the case at present.
Secondly, in my improved steam generator, I arrange the heating surfaces so that
the flame and heated gases may be made to impinge upon a larger area of plate than
is the case in generators in the existing method of construction where natural
circulation only is employed. When solid fuel is employed and in some cases where
liquid or gaseous fuel is employed, I effect this by employing water tubes, pockets, or
mid-feathers in and about the furnace, flame-box, and flues and provided with high
pressure water jets to play within the said tubes, pockets or mid-feathers, at the back
of the plates where the heat is greatest.
When liquid or gaseous fuel is used instead of employing one or more large nozzles
or jets to deliver the fuel to the furnace I employ a number of smaller nozzles or jets
so arranged that the flame may be distributed and made to impinge direct against
the plates forming the heating surface and exactly opposite such flame jets I arrange
at the back of the plates the high pressure water jets, in this way vertical heating
surface may be made as effective as horizontal surface and other portions of the non-
effective surface may in this way be converted into effective heating surface.

page_text: In some cases I construct the heating surfaces of my improved generator much
thinner at the point or zone where the flame and water jets come into operation, so
that the centre of the flame jet and the centre of the water jet would play respectively
on a surface, at right angles to and concentric with the jets, of much thinner material
than the body of the plate surrounding the same, and by having the plates thicker on
the spaces around and between these heating points or zones sufficient strength may
be preserved in the structure of the generator to carry the required pressure.
The water forced through these high pressure jets may be drawn entirely from the
contents of the generator or it may be mixed with the feedwater, or in some cases
where the generator is specially proportioned the water forced on to the heating
surfaces may be so regulated as to be equivalent or nearly so to the evaporative
capacity of the same, providing always that the quantity of the water so forced shall
be sufficient to keep the plates from overheating.
As already stated the high pressure water jet as herein described is applicable to
most, forms of steam boilers but in the case of a boiler where "Field circulating tubes,"
are employed I place a high pressure water jet at the end of the internal downcast
tube or at the end of an additional tube within each downcast tube. To effect this I
so arrange and proportion the sizes of the respective tubes that the natural circulation
and action of the "Field tubes," may not be interfered with when a low rate of steaming
is required, but when a higher rate of steaming with forced draught, is required, I then
employ forced circulation down the inner water jet, tubes or downcast tubes which
causes the water to impinge on the inner surface of the end of each outer tube, just
where the flame impinges and where the heat is most intense, this arrangement also
assists the circulation throughout the tubes and prevents overheating, in this way a
boiler constructed with "Field tubes," may be forced to a much higher rate of steaming
than is ordinarily the case.
I, RICHARD HEBER RADFORD, of 15, St. James' Row, Sheffield, in the County of York,
Mechanical Engineer, 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 :-
•
The objects of my invention are to construct a steam generator specially adapted
for either a high or low rate of steaming, also to reduce the weight and space occupied
in proportion to the power generated.
My invention is applicable to a great variety of steam generators, but is more
particularly applicable for use in a marine type of boiler, as for example, for torpedo
and despatch boats and other ships of war and the like in which the demand for steam
is sometimes sudden and urgent and the rates of steaming subject to considerable
variations.
I construct my improved steam generator so that it can be used either with natural
or forced draught and with either natural or forced circulation, thus, when a low or
moderate rate of steaming is required natural draught with either natural or forced
circulation may be employed and where a higher or express rate of steaming is
required both forced draught and forced circulation will be employed as circumstances
may require.
I effect this, Firstly, by providing a number of high pressure water jets so arranged

page_text: and distributed inside the generator in the vicinity of the most effective heating
surface, that when the heat is intensified to a degree sufficient to cause overheating
of the plates, water may be injected so as to impinge on the back of the plates with a
sufficient force to break up or prevent the harmful formation of spheroidal steam and
consequent overheating, thereby enabling a nuch greater draught to be employed,
with a corresponding higher rate of evaporation. This part of my invention is
applicable to a great number of existing types of steam generators and would enable
many such to employ much greater draught and work to a much higher rate of
steaming than is the case at present.
Secondly. In my improved steam generator I arrange the heating surfaces so that
the flame and heated gases may be made to impinge upon a larger area of plate than
is the case in generators in the existing method of construction where natural
circulation only is employed.
When solid fuel is employed and in some cases where liquid or gaseous fuel is
employed, I effect this by employing water tubes, pockets, or mid-feathers in and
about the furnace, flame-box and flues, and provided with high pressure water jets to
play within the said tubes pockets, or mid-feathers, at the back of the plates where
the heat is greatest.
When liquid or gaseous fuel is used instead of employing one or more large nozzles
or jets to deliver the fuel to the furnace, I employ a number of smaller nozzles or jets
so arranged that the flame may be distributed and made to impinge direct against the
plates forming the heating surface and exactly opposite such flame jets I arrange at
the back of the plates the high pressure water jets, in this way vertical heating surface
may be made ás effective as horizontal surface and other portions of the non-effective
surface may in this way be converted into effective heating surface.
In some cases I construct the heating surfaces of my improved generator much
thinner at the point or zone where the flame and water jets come into operation, so
that the centre of the flame jet and the centre of the water jet would play respectively
on a surface, at right angles to and concentric with the jets, of much thinner material
than the body of the plate surrounding the same, and by having the plates thicker
on the spaces around and between these heating points or zones sufficient strength
may be preserved in the structure of the generator to carry the required pressure.
The water forced through these high pressure jets may be drawn entirely from the
contents of the generator or it may be mixed with the feed-water. In some cases
where the generator is specially proportioned the water forced on to the heating
surfaces may be so regulated as to be equivalent, or nearly so, to the evaporative
capacity of the same, providing always that the quantity of the water so forced shall
be sufficient to keep the plates from overheating.
"
As already stated the high pressure water jet as herein described is applicable to
most forms of steam boilers but in the case of a boiler where "Field circulating
tubes are employed I place a high pressure water jet at the end of the internal
downcast tube or at the end of an additional tube within each downcast tube. To
effect this I so proportion the sizes of the respective tubes that the natural circulation
and action of the "Field " tubes, may not be interfered with when a low rate of
steaming is required, but when a higher rate of steaming with forced draught, is
required, I then employ forced circulation down the inner water jet tube or tubes
which causes the water jet to impinge on the inner surface of the end of each outer
tube, just where the flame impinges and where the heat is most intense, this arrange-
ment also assists the circulation throughout the tubes, and prevents overheating, in
this way a boiler constructed with "Field " tubes may be forced to a much higher
rate of steaming than is ordinarily the case.
Disclaimer. It is well known that when forced draught was first employed in
marine boilers some difficulty was experienced through the accidental over heating of
the tube plates and I believe that it was suggested that water jets should be employed
on the back of the tube plate to prevent such accidental overheating, but I am not
aware that this suggestion was ever carried into practice. I nevertheless, wish it to
be understood that I lay no claim to novelty for the application of any part of my

page_text: invention for the prevention of accidental overheating of the tube plates or any
portion of the heating surfaces of either marine or other types of steam boilers.
The nature of my said invention will be better understood on reference to the
accompanying two sheets of drawings, in which,
Fig. 1, is a cross section of a cylindrical steam boiler shewing the application of my
invention where solid fuel is employed under a powerful forced or induced draught.
Fig. 2, being a longitudinal section of the same.
Figs. 3 & 4, are similar views shewing the application of my invention where
liquid or gaseous fuel is employed in the form of jets impinging against the plates.
Fig. 5, is a section of a cylindrical boiler shewing the application of my invention
in combination with "Field" circulating tubes, in which an additional tube within
each downcast tube is employed for injecting a high pressure water jet at the end of
each outer tube where the flame impinges and where the heat would become most
intense in forced firing either with solid, liquid or gaseous fuel.
Fig. 6, illustrates a modification in the design of a "Field" circulating tube in
which the downcast tube can be employed either for natural or forced circulation,
this being effected by constructing the upper ends of the tubes somewhat after the
fashion of a two, three, or fourway cock. The downcast tubes being turned simul-
taneously by being connected together with gear wheels, pitch chains, or other
equivalent means so that the whole or groups, or rows, of tubes may be simultaneously
turned so as to act either with natural or forced circulation as may be required.
Fig. 7, illustrates a portion of the heating surface of a steam generator where the
plates are made thinner at the point or points or zone where the respective jets come
into operation.
The same letters refer to similar parts throughout the several views.
a is the shell of the boiler..
b is the furnace or flue.
1
cc are the high pressure water pipes provided with jets for forcing the water
against the surface of the plates.
.
dd are the connecting or service pipes for the same.
e is one of the valves by which the flow of water is regulated.
ff are the pipes so arranged that the flame of the liquid or gaseous fuel may be
distributed and made to impinge against the plates forming the heating surface.
gg being the supply or connecting pipes for the supply of such liquid or
gaseous fuel and their stimulants air, or steam as the case may be.
h is the outer pipe of a "Field " tube.
is the inner or downcast pipe.
i is the additional high pressure pipe employed for forced circulation when a higher
rate of steaming is required.
kis the supply or connecting pipe serving the whole or a group of such pipes.
I is the shell or cap of a specially constructed "Field " tube carrying the plug end
of the downcast tube which can be used for either natural or forced circulation.
mmm are the orifices in the plug which, when open to the water space in the
boiler allow of natural circulation taking place through the downcast pipe, i, and
when closed the downcast. pipe can be employed for forced circulation by opening
communication with the high pressure pipes with which it is previously connected,
the direction of the forced circulation being indicated by the dotted arrow.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim, is:
1. In a steam generator, where solid fuel is employed under powerful forced or
induced draft so as intentionally to cause the flame or heated gases to impinge upon
the plates forming the heating surface. The combination and arrangement of a
number of high pressure water jets on the back or water side of such plates in the
vicinity or immediately opposite such impinging flame or heated gases, substantially
in the manner and for the purposes as herein described and illustrated.

page_text: 2. In a steam generator, where liquid or gaseous fuel is employed, the
arrangement of a number of high pressure water jets on the back or water side of
the plates forming the heating surface in combination with a number of fuel jets on
the front or fire side of such plates. The water jets on one side of the plates being
placed immediately opposite the fuel jets on the other side of the plates substantially
in the manner and for the purposes as herein described and illustrated.
3. In a steam generator where high pressure water jets in combination with fuel
jets are employed as described in Claim 2, constructing the plates forming the
heating surface or surfaces thinner at the point or points or zone where the respective
jets come into operation and are concentrated, substantially in the manner and for
the purposes as herein described and illustrated.
4. In a steam generator where, circulating water tubes of the "Field" type are
employed arranging and placing a high pressure water jet at the end of the internal
downcast tube or at the end of an additional tube within each downcast tube so that
when forced circulation is required a high pressure water jet may be directed on the
inner surface of the end of each water tube, just where the flame impinges and where
the heat is most intense, substantially in the manner and for the purposes as.herein
described and illustrated.
D
.