IMPROVEMENTS IN MARINE STEAM BOILERS
Year: 1878

page_text: LETTERS PATENT to Charles Smith, of Hartlepool, in the County of Durham,
Engineer, for the Invention of "IMPROVEMENTS IN MARINE STEAM BOILERS,"
Sealed the 1st October 1878, and dated the 10th April 1878.
PROVISIONAL SPECIFICATION left by the said Charles Smith at the Office
of the Commissioners of Patents on the 10th April 1878.
CHARLES SMITH, of Hartlepool, in the County of Durham, Engineer.
MENTS IN MARINE STEAM BOILERS."
"IMPROVE-
This Invention relates to steain boilers specially designed for marine purposes, and
has principally for its objects to render such boilers simple, safe, economical in fuel,
and durable.
The main evaporating part of a modification of boiler made with the improve-
ments consists of a cylindrical shell which is placed with its axis horizontal, and is
traversed by comparatively small tubes through which the fire gases pass. Two
furnaces are placed below the lateral parts of the main boiler shell, and being
formed inside cylindrical iron casings lined with fire-brick are altogether dry or
apart from any water space. At their back ends the furnaces communicate with a
combustion chamber, and the fire gases pass from the upper part thereof through
the tubes of the main boiler shell to a smoke box and uptake at the front, the space
for stoking thus also serving for access to the tubes for cleaning or repairing them,
as in some existing marine boilers. To prevent radiation from the exteriors of the
furnace shells these are by preference cased in or partly cased in with another iron
shell, leaving an intervening space between the two iron shells, which space is filled
in with a suitable non-conducting substance, such as infusorial earth or kieselguhr.
The combustion chamber at the back is also of brickwork, and is by preference
additionally encased like the furnace shells; or the kieselguhr may be packed
between the brickwork and a single iron shell,

page_text: With the improved construction herein-before described the fuel is burned in a
more complete and effective manner than in ordinary steam boiler furnaces, the
heated state acquired by the interior of the fire-brick linings of the furnaces and
combustion chamber insuring the ignition of all the combustible constituents of the
fuel, thus economising the fuel and preventing much emission of smoke.
Also, when the furnace doors are opened for introducing fresh fuel the cold air
entering becomes heated by the fire-brick lining before it reaches the evaporating
surfaces of the main boiler, and cannot injure those surfaces as in ordinary boilers.
In cases where it may be desired to increase the effects arising from heated fire-
bricks in boiler furnaces and combustion chambers, as herein-before described,
screens of fire-brick, pigeon-holed for the passage of the fire gases, may be inter-
posed in the back part of the furnaces or in the combustion chambers, or such screens
may consist of tiers of fire-clay tubes instead of pigeon-holed brick work. The
effect of these screens in either case is the equalising of the temperature of the
gases before they reach the evaporating surfaces, the screens taking up heat when
the fire is at its best, and giving it out when the fires are green or when the fire-
doors are open, and admit a considerable quantity of cold air, the action of the hot
brickwork being what is known as "regenerative."
This part of the Invention, namely, the interposition of screens of perforated
brickwork or of fire-clay tubes at the back of and between the furnaces and the
evaporating tubes is also applicable to the common forms of boilers having internal
furnaces, the effect of such screens being to secure the more complete combustion of
the fuel gases, and to prevent changes of temperature from acting on the evaporating
tubes, and causing them to leak at their junctions with the tube plate. Where
such screens are fitted access to the combustion chambers on the further side of the
screens may be obtained by means of man-hole doors through the combustion
chamber sides in boilers having dry combustion chambers, or by man-hole doors
through the water spaces in boilers having internal or water-cased combustion
chambers.
Any number of main boiler shells, each with one or two of the "dry" or brick-
enclosed separate furnaces may be grouped together to make up the power required
for any steamer ; or instead of each furnace or pair of furnaces working in connection
with one main boiler shell it or they may be applied to two such boiler shells placed
back to back with the combustion chamber between them.
The boiler shells may be oval or of other suitable forms instead of cylindrical;
and the furnaces may also be made of other forms than cylindrical if found more
convenient.
It is an important advantage of the improved construction herein-before described
that for a given size of main boiler shell and without adding to the space occupied,
.excepting the small extra height required for the furnaces, the space for which can
in most cases be afforded without any inconvenience, the effective heating surface is
very largely increased, the spaces ordinarily occupied by furnaces and combustion
chambers being utilised for tubes.
The main boiler shell with its tubes is obviously of the simplest construction, and
all the parts of it may be put together in the most suitable manner for strength
and safety, all the difficulties and risks inseparable from either external or internal
plates subjected to direct fire heat being avoided, and this with increased instead of
diminished advantage as regards the economical generation of steam. The risk of
collapse of furnaces, which is an important and dangerous feature in boilers having
internal furnaces and carrying high steam pressures, is also in this improved
construction completely avoided.
It is another important advantage of the improved construction herein-before
described that the boilers are more lasting and have less tear and wear owing to the
corporation and consequent circulation of the water being effected so closely to the
bottom of the boiler shell. The whole of the shell of the boiler is thereby kept
more nearly at a uniform temperature, thus avoiding the straining caused by

page_text: irregular expansion in boilers having internal furnaces, such irregular expansion
being due to the comparatively large quantity of water that lies dead below the
levol of the fires or beyond the influence of the ebullition and circulation in the
boiler.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Charles Smith in the Great Seal Patent Office on the 8th October
1878.
CHARLES SMITH, of Hartlepool, in the County of Durham, Engineer. "IMPROVE-
MENTS IN MARINE STEAM BOILERS."
My said Invention relates to steam boilers specially designed for marine purposes,
and has principally for its objects to render such boilers simple, safe, economical, and
durable.
The main evaporating part of a simple modification of boiler made with my im-
provements consists of a cylindrical shell which is placed with its axis horizontal,
and is traversed by comparatively small tubes through which fire gases pass. Two
furnaces are placed below the lateral parts of the main boiler shell, and being
formed inside of cylindrical iron casings lined with fire-brick are altogether dry or
apart from any water space. At their back ends the furnaces communicate with a
combustion chamber, and the fire gases pass from the upper part thereof through
the tubes of the main boiler shell to a smoke box and uptake at the front, the space for
stoking thus also serving for access to the tubes for cleaning or repairing them as
in some existing marine boilers.
With the improved construction, herein-before partly and herein-after more fully
described, the fuel is burned in a more complete and effective manner than in
ordinary steam boiler furnaces, the heated state acquired by the interior of the fire-
brick linings of the furnaces and combustion chamber insuring the ignition of all
the combustible constituents of the fuel, thus economising the fuel and preventing
inuch emission of smoke.
Also when the furnace doors are opened for introducing fresh fuel the cold air
entering becomes heated by the fire-brick lining before it reaches the evaporating
surfaces of the main boiler, and cannot injure those surfaces as in ordinary
boilers.
In cases where it may be desirable to increase the effects arising from heated
fire-bricks in boiler furnaces and combustion chambers, as herein-before described,
screens of fire-brick, pigeon holed for the passage of the fire gases, may be interposed
in the back parts of the furnaces, or in the combustion chamber; or such screens
may consist of tiers of fire-clay tubes instead of pigeon-holed brickwork. The
effect of these screens in either case is to equalise the temperature of the gases before
they reach the evaporating surfaces, the screens taking up heat when the fire is
at its best, and giving it out when the fire is green, or when the fire doors are open

page_text: and admitting a considerable quantity of cold air, the action of the hot brickwork
being what is known as "regenerative."
This part of my Invention, namely, the interposition of screens of perforated
brickwork or of fire-clay tubes at the back of and between the furnaces and the
evaporating tubes, is also advantageously applicable to the common forms of boilers
having internal furnaces, the effect of such screens being to secure the more
complete combustion of the fuel gases, and to prevent changes of temperature from
injuriously acting on the evaporating tubes and causing them to leak at their
junctions with the tube plates. Where such screens are fitted access to the com-
bustion chamber on the further or inner sides of the screens may be obtained by
means of man-hole doors through the combustion chamber sides in boilers having dry
combustion chambers, or by man-hole doors through the water spaces in boilers
having internal or water-cased combustion chambers.
Any number of main boiler shells, each with one or two of the "dry" or brick
enclosed separate furnaces, may be grouped together to make up the power required
for any steamer; or instead of each furnace, or pair, or sets of furnaces working in
connection with one main boiler shell, it or they may be applied to two such boiler
shells, either placed back to back with the combustion chamber between them, or
placed side by side with the combustion chamber common to and at the back of
both.
The boiler shells may be oval or of other suitable forms instead of cylindrical, and
the furnaces may also be made of other forms than cylindrical if found more con-
venient.
It is an important advantage of my improved construction that for a given size
of main boiler shell, and without adding to the space occupied, excepting to the
small extra height required for the furnaces, the space for which can in most cases
be afforded without any inconvenince, the effectivo heating surface is very largely
increased, the spaces ordinarily occupied by furnaces and combustion chambers
being utilised for tubes.
The main boiler shell with its tubes is obviously of the simplest construction, and
all the parts of it may be put together in the most suitable manner for strength and
safety, all the difficulties and risks inseparable from either external or internal
plates subjected to direct fire heat being avoided, and this with increased, instead
of diminished, advantage as regards the economical generation of steam. The risk of
collapse of furnaces, which is an important and dangerous feature in boilers having
internal furnaces and carrying high steam pressures, is also in my improved con-
struction completely avoided.
It is another important advantage of my improved construction that the boilers
are more lasting, and have less tear and wear, owing to the evaporation of the
water being effected so closely to the bottom of the boiler shell. The whole of the
shell of the boiler is in consequence kept inore nearly at a uniform temperature,
thus avoiding the straining caused by irregular expansion in boilers having internal
furnaces, such irregular expansion being due to the comparatively large quantity of
water that lies dead and comparatively cold below the level of the fires, or beyond
the influence of the ebullition and circulation in the boiler.
And in order that my said Invention and the manner of performing the same
may be properly understood, I hereunto append four Sheets of explanatory Drawings
to be herein-after referred to, and representing three modifications of my improved
marine boilers. In these Drawings the same reference numerals are used to mark
the same or like parts wherever they are repeated.
Figure 1, ou Sheet 1 of the accompanying Drawings, represents a single boiler
as made according to my Invention, one half of the Figure being a front elevation
with the smoke box door or front removed, and the other half a vertical section
as through the combustion chamber at the back.
Figure 2, on Sheet 2, is a vertical section as at right angles to Figure 1.
The main part of the boiler is a cylindrical shell 1 with vertical front and back
ends 2, 3, and having its lower part occupied by horizontal fire gas tubes 4, which

page_text: are fixed in the ends 2, 3, in the usual way, some of the tubes being made to act
as stays, whilst additional stays 5 are fixed across the upper part above the tubes.
Two furnaces 6 are placed below the lateral parts of the main boiler shell 1, and
are formed inside of cylindrical iron casings 7 lined with fire-brick 8, being dry
or unsurrounded by water spaces. At their back ends the furnaces 6 communicate
with a combustion chamber 9, from the upper part of which the fire gases pass
into the tubes 4, and this combustion space 9 is also formed in brickwork 10 built
inside of an iron shell 11. To prevent radiation from the exteriors of the furnace
shells 7 these are, by preference, cased in or partly cased in with another iron
shell 12, leaving an intervening space between the two shells 7, 12, which space is
filled in with a suitable non-conducting substance, such as infusorial earth or
kieselguhr. A similar space is also, by preference, left between the brickwork
walls 10 of the combustion chamber 9 and the external shell 11, and is packed
with kieselguhr or other suitable non-conducting substance. After passing through
the tubes 4 the fire-gases pass up the uptake 13 in the usual way, and a steam
chest or dome 14 is as usual fitted to the top of the main boiler shell 1.
Figures 3 and 4, on Sheet 3 of the accompanying Drawings, are front and side
clevations of a pair of my improved boilers combined back to back, each constructed
and arranged as herein-before described with reference to Figures 1 and 2, but with
one combustion chamber (9) between and common to both, and with the uptakes 13
leading into one funnel.
The boilers are represented as in position in a ship, which is shown in section.
Figure 5, on Sheet 4 of the accompanying Drawings, is a front elevation, and
Figure 6 is a vertical section, as at right angles to Figure 5, showing a pair of my
improved boilers combined side by side. In this modification there are three
furnaces 6 (in dry casings), the middle one being made larger than the other two.
All three furnaces G communicate with one combustion chamber 9 at the back, and
in other respects the arrangement is substantially the same as in the other
modifications.
Having thus particularly described my said Invention, and the manner of per-
forming the same, I have to state that I do not restrict myself to the precise
details herein described or 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 arranging or combining together of the parts of marine steam boilers,
substantially in the improved manner herein-before described.
2. The combination of one or more main boiler shells traversed by firo gas tubes,
with one or more furnaces surrounded by brickwork, or "dry," which furnace is,
or furnaces are, beneath the main boiler shell or shells, and communicates with the
tubes by a combustion chamber constructed in brickwork, all substantially as
herein-before described.
3. The employment of fire-brick screens in connection with the furnaces of
marine steam boilers, substantially as and for the purposes herein-before described.
In witness whereof, I, the said Charles Smith, have hereunto set my hand
and seal, this Seventh day of October, in the year of our Lord One
thousand eight hundred and seventy-eight.