IMPROVEMENTS IN STEAM GENERATORS GENERATORS
Year: 1873

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn
Fields, in the County of Middlesex, Gentleman, for the Invention
of "IMPROVEMENTS IN STEAM GENERATORS."-A communication from
abroad by Louis Marie Théophile Riot and Philippe Roux, both of
Paris, in the Republic of France.
Sealed the 5th September 1873, and dated the 24th March 1873.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson
at the Office of the Commissioners of Patents, with his Petition, on
the 24th March 1873.
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the
County of Middlesex, Gentleman, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN STEAM GENERATORS," a communication
to me from abroad by Louis Marie Théophile Riot and Philippe Roux,
both of Paris, in the Republic of France, to be as follows:-
This Invention relates to improvements in the general construction
and arrangement of steam generators, whereby a large amount of steam

page_text: may be generated with a small consumption of fuel. Calcureous deposit
upon the sides of the generator in direct contact with the fire is pre-
vented by causing a forced and constant circulation of the water to take
place, and the heat is applied under the most favorable conditions by
causing it to act upon thin films of water.
The improved generator may be constructed either as a vertical or as a
horizontal boiler. In the vertical arrangement the fire-box is provided
behind the grate bars with an upright transverse partition of fire-brick
extending nearly to the roof thereof in order to ensure the traversing of
the products of combustion through a given course before entering the
chimney, the flue leading to which may be situate below the level of
the fire-bars. The ash-pit is closed in front by adjustable double sliding
doors, which serve to regulate the draught. The roof of the fire-box
forms a tube plate for the reception of a number of vertical tubes or
tubular pockets closed at the bottom, into which are suspended other
tubes open at both ends and secured at their upper ends into a cap or
hood, which covers the crown or roof of the fire-box. Openings are
made round the sides of the said cap or hood for the circulation of the
more highly heated water therethrough, and a sheet metal envelope is
secured all round the cap or hood above the said openings, such envelope
descending round the sides of the fire-box to within a short distance
from the bottom of the boiler so as to enclose a thin film of water, which
is subjected to the direct heat of the fire. This film of water being
highly heated circulates upwards in a continuous manner through the
hood, and thence up a pipe which leads from the top of the hood into a
depositing box or chamber situate a short distance above the hood, in
which box all the calcureous deposit is precipitated, and is removed
thence through a blow-off pipe and cock at intervals. The top of the
pipe leading into the depositing box is provided with a cup or deflector
to direct the water downwards as it enters; and an overflow pipe is
provided on one side of the box for the escape of the water back into
the boiler. The top of the depositing box is perforated with numerous
holes to admit the steam pressure therein.
The thin films of water contained between each of the before mentioned
inner and outer tubes depending from the roof of the fire-box and from
the hood respectively also rises by reason of its more elevated temperature
and enters the depositing box along with that from the film surrounding

page_text: the fire-box, thus a constant circulation or ascentional movement of the
water is maintained.
In the horizontal arrangement of the improved generator a series of
horizontally disposed double tubes are employed, through the inner ones
of which the products of combustion pass on their way to the chimney,
and impart heat to a thin film of water contained between the exterior
of the inner tubes and the interior of the outer or surrounding tubes,
lateral openings being made in the outer tubes at opposite ends thereof
for the free circulation of the water therethrough.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Henry Johnson in the Great Seal Patent
Office on the 23rd September 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of
Middlesex, Gentleman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-fourth day of March, in the
year of our Lord One thousand eight hundred and seventy-three, in the
thirty-sixth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said John Henry Johnson, Her special
license that I, the said John Henry Johnson, my executors, adminis-
trators, and assigns, or such others as I, the said John Henry Johnson,
my executors, administrators, or assigns, should at any time agree with,
and no others, from time to time and 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 Invention for "IMPROVE-
MENTS IN STEAM GENERATORS," a communication to me from abroad by
Louis Marie Théophile Riot and Philippe Roux, both of Paris, in the
Republic of France, upon the condition (amongst others) that I, the said
John Henry Johnson, my executors or administrators, by an instrument
in writing under my hand and seal, should particularly describe and
ascertain the nature of the said Invention, and in what manner the

page_text: 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 John Henry Johnson, do hereby
declare the nature of the said Invention, and in what manner the t
same is to be performed, to be particularly described and ascertained
in and by the following statement, reference being had to the accom-
panying Drawings and to the letters and figures marked thereon, that
is to say:

page_text: A is the outer casing of the generator, in the interior of which there
are disposed the fire chamber B and the receptacle C, which is intended
for the reception of the calcareous deposits. The fire chamber is divided
at the back of the grate bars D by a partition E composed of refractory
material, the effect of which is to force the gases from the fire to take a
certain course before allowing them to escape by the chimney. The
combustion is regulated by means of a double sliding door M, the
opening of which may be modified at will. The roof of the fire chamber
forms a tube plate and receives a series of tubes a, a, in the interior of
which there are suspended other smaller tubes 6 having their point of
support on a cap or hood F, which covers the roof of the fire chamber,
and is provided on its periphery with a series of apertures c, the function
of which will be herein-after described. On the cap or hood F and over
the apertures c there is fitted a sheet metal casing d, between which
and the vertical sides of the fire chamber a small space is left, which
casing d thus covers the fire chamber over the whole of its circumference
to within a short distance of the bottom. From the top of the cap or
hood F rises the pipe g, which is surmounted by a cap h, and opens
into the receptacle C, the top of which is perforated with a number of
small holes. The receptacle C is provided with an overflow tube h
and with a pipe k, by which pipe the calcareous deposits contained in the
receptacle are removed under pressure. The steam generator being thus
arranged it remains to describe under what conditions the vaporization

page_text: passes through its perforated top into the upper part of the generator,
whilst the calcareous deposits which are carried along by the constant
circulation of the liquid collect by reason of their greater density in the
bottom of the receptacle, whence they may be readily removed by the
whilst the calcareous deposits which are carried along by the constant
circulation of the liquid collect by reason of their greater density in the
bottom of the receptacle, whence they may be readily removed by the
pipe k.
It will be seen from the Drawing that this new system of steam
generator is very simple in its construction, and that the whole of the
parts may be inspected, removed, and replaced with facility.
The example I have described is that of a vertical boiler, but the
Invention may be applied horizontally, as shewn by the red lines. In 1
this case the products of combustion are forced to traverse a series of
horizontal tubes a¹, which are secured by rings at their extremities in
tube plates 6, 6¹, and are surrounded by tubes c', the latter tubes being
frce at one end and kept separate from the tubes a¹ by the depth of a
number of rivet heads & disposed for that purpose. An aperture e¹ at 1
one end admits of the entrance of the liquid, and an aperture f¹ placed
at the opposite end allows the hottest liquid to escape, so as to obtain
as in the case of the vertical boiler a forced and constant circulation of
the liquid to be vaporized.
Having now described and particularly ascertained the nature of the 2
said Invention, and the manner in which the same is or may be used
or carried into effect, I would observe in conclusion that what I
consider to be novel and original and therefore claim as the Invention
secured to me by the herein-before in part recited Letters Patent is,―
First. The peculiar arrangement of parts herein-before described and 2
illustrated by the Drawing, whereby a large quantity of steam is pro-
duced with a small expenditure of fuel.
Secondly. Preventing calcareous deposits on the sides of the boiler
in direct contact with the fire by maintaining a forced and constant
circulation of the liquid produced, substantially in the manner herein-
before described and illustrated by the Drawing.
Thirdly. Utilizing the caloric under the best conditions by causing it
to act directly on very thin films of liquid, substantially as herein-before
described and illustrated by the Drawing.

page_text: Fourthly. The general construction and arrangement of steam generator,
substantially as and for the purposes herein-before described and illus-
trated by the Drawing annexed.
In witness whereof, I, the said John Henry Johnson, have to
this my Specification set my hand and seal, this Twentieth day
of September One thousand eight hundred and seventy-three.