Improvements in Steam Generators.
Year: 1892

page_text: Date of Application, 8th Apr., 1892
Complete Specification Left, 9th Jan., 1893-Accepted, 4th Mar., 1893
PROVISIONAL SPECIFICATION.
Improvements in Steam Generators.
I, JAMES YATE JOHNSON, of 47 Lincoln's Inn Fields, in the County of Middlesex,
Gentleman, do hereby declare the nature of this invention (which has been com-
municated to me from abroad by La Société Anonyme des Forges et Chantiers de
la Méditerranée) to be as follows:-
The present invention relates to an arrangement of high pressure cylindrical
generators, with or without forced draught possessing all the advantages of the
return flame type without the disadvantages which have heretofore been experienced
with this class of boiler.
With this object the generators are combined with external or independent com-
bustion chambers and are preferably arranged in pairs with the furnaces in the
middle or between the generators as hereinafter explained.
Each generator of the pair is heated by an independent furnace specially con-
structed or lined with brickwork to protect it from damage when at sea.
This furnace or combustion chamber is placed over an ash pit constructed with
metal plates to which air is admitted at the sides through balanced flaps or doors
which ensures proper combustion of the coal. The bottom of the ash pit is
preferably in the form of a basin for the reception of water which prevents burning
of the fire bars when a forced draught is employed.
The generator proper is composed of a cylindrical body or shell which may be
readily constructed with three sheets composing an outer or cylindrical casing made
in two parts one forming the water space and the other the steam space, a front
plate or tube sheet in one piece and a back plate or tube sheet likewise in one
piece.
In the lower part of the shell there are corrugated flues conducting the flame
from the furnace through the boiler after which the flame returns through flue
tubes arranged above the said corrugated flues and which may be of very small
diameter owing to their limited length.
The numerous advantages arising from this arrangement will be readily
understood.
The construction of the boiler shell is greatly simplified and the leakages to
which seams in the furnace and smoke box ends are liable are obviated. The
furnace or combustion chamber, being independent the coal is not brought into
direct contact with the boiler plates which are consequently protected from
destruction.
The area of the combustion chamber can be increased if required by simply
augmenting the distance between the cylindrical generators.
The corrugated flue tubes may be made of unequal or different diameters so as to
reduce as much as possible the volume of water in the lower part of the boiler.
The flame being caused to circulate in these tubes in contact with every part of
their circumference the body of water in the boiler uniformly heated throughout.
The small tubes may be fixed in the tube sheet at the furnace end by the
Caramon process and may be readily inserted or removed either on land or
at sea.
When the boilers are intended for working with a natural draught the ash pans
are perforated with holes on every side and have a regulating door in the front.
On the other hand when the boiler is working with a forced draught the openings
in the ashpit.are provided with automatically closing doors or valves.
The air under pressure supplied by the fans passes through a passage in the
smoke box so as to be heated before reaching the grate. This air enters at the end

page_text: farthest from the furnace door. The tube sheet is consequently neither exposed to
direct contact with and radiation from the flame nor to currents of cold air as is
the case especially in boilers of the locomotive type and leakages at tubes are thus
obviated.
As another advantage of the improved arrangement may be mentioned the
economy of space and consequent reduction of weight relatively to the effect
produced. This is a point of the utmost importance in warships with armoured
decks.
In building these vessels the ordinary cylindrical boilers owing to their size have
to be put in before constructing the deck and when they have to be renewed an
extremely expensive amount of work has to be done throwing the ship out of service
for about six months.
The casing can be arranged in such a manner as to provide in the stoke hole a
temperature as low as that of the best ventilated stoke holes.
Dated this 8th day of April 1892.
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, W.C., Agents.
COMPLETE SPECIFICATION.
Improvements in Steam Generators.
I JAMES YATE JOHNSON of 47 Lincoln's Inn Fields in the County of Middlesex
Gentleman do hereby declare the nature of this invention (which has been com-
municated to me by La Société Anonyme des Forges et Chantiers de la
Méditerranée of Paris in the Republic of France) and in what manner the same
is to be performed to be particularly described and ascertained in and by the
following statement :-
The type of marine boiler with return flues at one time commonly employed has
gradually been abandoned owing to the demand for higher pressure and the
necessity for reducing the weight especially in ships of war which has led to the
construction of generators working with a forced draught. Under these conditions
the wear and tear of the parts becomes excessive when the old type of boiler is
employed.
The present invention relates to an improved arrangement of high pressure
cylindrical generators capable of working either with or without forced draught
and possessing all the advantages of the return flame type without the disadvantages
which have heretofore been experienced with this class of boiler. With this object
the cylindrical generators are combined with external or independent combustion
chambers or furnaces and are preferably arranged in pairs with the furnaces in the
space between the boilers as hereinafter explained.
And in order that this invention may be fully understood I shall now proceed to
more particularly describe the same with reference to the accompanying drawings
the same letters of reference indicating corresponding parts in all the figures.
Figure 1 of the accompanying drawings represents in elevation and partly in
vertical section on the line 1-2 Figure 2 one of a pair of generators constructed
with independent furnaces according to this invention.
Figure 2 represents the arrangement of the pair of generators, the furnace aud
so much of the generator on the right hand as is shewn in the drawing being
represented in elevation and the furnace and generator on the left hand being drawn
in section taken on the line 3-4 Figure 1.
Each generator of the pair is heated by an independent furnace A specially con-
structed with brickwork arranged as represented in the drawing, so as to enable it
to resist the wear of working. This furnace or combustion chamber is placed over
an ash pit B constructed with metal plates and to which air is admitted at the sides
through balanced flaps or doors so as to ensure proper combustion of the fuel.

page_text: The bottom of the ash pit is preferably arranged to contain water in order to
prevent burning of the fire bars when a forced draught is employed.
The generators or boilers prope are each composed of a cylindrical body or
shell C. The cylindrical part or sides are preferably built up with two sheets c
and c¹ the sheet c enclosing the water space and the sheet c' enclosing the steam
space. The front end is closed by a circular tube plate or sheet d made in one
piece and the rear end is closed by a similar tube sheet e.
In the lower part of the shell corrugated flues D conduct the flame from the
furnace A to a chamber D' at the rear whence the flame passes into flue tubes E.
which owing to their limited length are enabled to be made of relatively small
diameter. These tubes discharge the products of combustion into the smoke stack
indicated by dotted lines at K.
The numerous advantages arising from this arrangement will be readily under-
stood.
The construction of the boiler shells is greatly simplified and the absence of
seams in the furnace and smoke box ends removes the liability to leakage at these
points. The furnace or combustion chamber being independent of or outside the
boilers the coal is not brought into direct contact with the boiler plates which are
consequently protected from burning or injury or accidents arising from this cause.
The area of the combustion chambers can be increased if required by simply
augmenting the distance between the cylindrical boilers and does not involve that
augmentation of diameter in the boiler shell which is necessary in order to enlarge
the area of the fire grate in boilers with internal combustion chambers and which
also involves an increase in the weight of the boiler and of the water which it
contains.
The corrugated flue tubes D may be made of any suitable diameter with a view
to reducing as much as possible the volume of water in the lower part of the boiler.
The flame being caused to circulate in these tubes in contact with every part of
their circumference the body of water in the boiler is uniformly heated throughout
whereas with internal furnaces the water at the bottom of the boiler remains
relatively cold even when the boiler is under pressure unless special arrangements
are employed to provide against this, such arrangements being usually uncertain
in their action and always complicating the construction.
The small tubes E are preferably fixed in the tube sheet at the furnace end by
the Caramon process and may be readily inserted or removed either at sea or on
land. Their small diameter enables a large heating surface to be obtained in a
small space. The design of the boiler is such as to enable diagonal stays (which
are generally a cause of leakage) to be completely dispensed with.
When the boilers are intended for working with a natural draught the ash pans
are perforated with holes on every side and have a regulating door or valve in the
front. On the other hand when the boiler is working with a forced draught the
openings in the ash pit are provided with automatically closing doors or valves.
The air under pressure supplied by the fans passes through a passage in the
smoke box so as to be heated before reaching the grate. This air enters at the
end furthest from the furnace door. The tube sheet is consequently neither exposed
to direct contact with and radiation from the flame nor to currents of cold air as is
the case especially in boilers of the locomotive type and leakages at tubes from
these causes are thus obviated.
As another advantage of the improved arrangement may be mentioned the
economy of space and consequent reduction of weight relatively to the effect
produced. This is a point of the utmost importance in war ships with armoured
decks.
In building these vessels the ordinary cylindrical boilers owing to their size have
to be put in before constructing the deck and when they have to be renewed an
extremely costly amount of work has to be done throwing the ship out of service
for about six months.
A generator arranged according to this invention suitable for the largest size of

page_text: armoured vessel need not exceed about three metres in diameter by 1.80 metres in
length for example so that the opening for the chimney is sufficient for introducing
the boiler.
All repairs can be effected on board as easily as on land. The details of the
casing are not illustrated in the drawing but they are arranged in such a manner
as to provide in the stoke hole (which with this arrangement is under atmospheric
pressure only) a temperature as low as that of the best ventilated stoke holes.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
First. The arrangement of cylindrical generators or boilers combined with
independent furnaces and capable of working either with a natural draught or
with a forced draught substantially as hereinbefore described and represented in the
accompanying drawings.
Second. The combinations and arrangements of parts constituting the improve-
ments in steam generators substantially as herein before described.
Dated this 9th day of January 1902
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, Agents.