IMPROVEMENTS IN THE METHOD OF AND
Year: 1875

page_text: LETTERS PATENT to Daniel Frank Mosman, of Chelsea, in the County
of Suffolk, in the State of Massachusetts, in the United States of
America, for the Invention of "IMPROVEMENTS IN THE METHOD OF AND
COMPLETE SPECIFICATION filed by the said Daniel Frank Mosman
at the Office of the Commissioners of Patents, with his Petition
and Declaration, on the 1st March 1875, pursuant to the 9th
Section of the Patent Law Amendment Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, DANIEL
FRANK MOSMAN, of Chelsea, in the County of Suffolk, and State of
Massachusetts, in the United States of America, send greeting.
WHEREAS I am in possession of an Invention for "IMPROVEMENTS IN
THE METHOD OF AND APPARATUS FOR GENERATING AND UTILIZING STEAM," and
have petitioned Her most Excellent Majesty Queen Victoria to grant
unto me, my executors, administrators, and assigns, Her Royal Letters
Patent for the same, and have made solemn Declaration that I am the
first and true Inventor thereof.

page_text: safety valve N, as is also the boiler B, as shown at O, the positions of
the boilers however being for convenience reversed end for end, and the
second boiler, or rather heater, being entirely closed to access from the
atmosphere.
The exhaust pipe of the engine is shown at P as discharging into the
lower part of the water space or chamber L of the structure H, and as
I condense and reconvert into water this exhaust steam I require the
injection into said water space of but little water from an outside source,
and this may be provided by any suitable injector or pump and from
any suitable source after the usual manner of operating steam boilers.
I prefer that the water within the chamber L shall stand at the point
indicated therein in the Drawings, and the steam pump for conveying
this water to the generator B is shown at Q as situated between the two,
the steam supply pipe by which such pump is driven being shown at R
as a branch of the pipe C; the exhaust pipe of such pump being shown
at S, the draft pipe from the water chamber L to the pump at T, and
the delivery pipe from the pump to the generator B at V.
The pipe T leads preferably from a point somewhat elevated above the
bottom of the water chamber L in order that any sediment which may
collect in the bottom of such chamber shall not be carried by and with
the water which flows through the pump into the generator, and by this
means I gain a very important point attaching to my Invention, that of
entirely preventing sediment in the generator. I obtain this result from
the fact that there is no ebullition in the chamber L to disturb the feed
water therein, and the influx of fresh water is very limited.
The space at the rear end of the structure H, into which the flues K
discharge, is shown at W as closed in lieu of being open, and serving as
a discharge for the smoke and waste products of combustion, as is the
case with the generator B, and I connect this space W by a hot air
conduit X with the ash-pit Y of the said generator. The air that is
admitted to the furnace I of the generator B to support combustion of
its fuel after its fire is started and water is heated to the boiling point
is supplied through the flues K, chamber or space W, and conduit X.
Should the water in the chamber L stand at a point above the cylinder
of the engine, which in practice will seldom take place, a check valve
opening outward should be placed in the exhaust pipe P.

page_text: The above description embraces the mechanical construction of an
apparatus which I have employed in carrying out my experiments, but
this form of apparatus is not compulsory, as I can depart from it to a
considerable extent without losing sight of the principle of my
Invention.
The operation of the apparatus may be briefly stated, assuming that
the water supplied to the boiler B and the heater H is at a temperature
of 32° Fahrenheit, and the height of the water in the two being as
shown in the Drawings:-
A fire is built in the furnace D and the water in the boiler B vaporized
until desired pressure, for example, sixty pounds to the square inch
generated, the air for supplying combustion within the furnace being
furnished through the ash-pit until the water in the boiler is raised to
the vaporizing point, when draft through the ash-pit is shut off and is
supplied through the flues K and conduit X before-named.
Steam being let on to the engine performs its office therein and
exhausts through the pipe P into the water contained within the
chamber L of the structure H, and parting with its heat, both sensible
and latent, begins the work of raising this water to the temperature of
1148, at which I supply it to the boiler with a pressure of one pound in
the heater H, which is about equal to exhausting into or against the
atmosphere. A portion of the heat contained in the exhaust steam thus
admitted to the chamber L is given up to the water, and a portion of the
steam, varying of course with circumstances, passes upward through the
superincumbent body of water and circulates about the flues K, but has
no access to the atmosphere through the safety valve N. The back
pressure upon the piston of the engine is due to the resistance which
the body of water in the chamber L offers, which is very slight and
hardly worth calculating, and to the extent to which the valve N is
weighted. The exhaust steam entering the structure H raises the
temperature of the feed water in the latter until one pound pressure is
reached, or such pressure as the valve N is weighted to produce.
All excess of heat from the exhaust steam, whether from leaking of
engine into exhaust pipe or other causes, which is not taken up by the
tubes K, blows off through the safety valve N, and the heat within the
structure lowers until the pressure is reduced, when the exhaust again
begins to condense, and so on as before.

page_text: As I assume that the engine is running with a pressure of sixty
pounds, I require practically no pressure within the chamber L, but as
the safety valve must indicate some degree of pressure in order that I
may determine whether or not the heat within such chamber reaches
the vaporizing point I weight the valve to blow off at one pound, and
consequently the back pressure upon the engine piston will be one.
pound. The water within the chamber L is pumped therefrom by the
pump Qinto the generator B, to be therein again vaporized and returned
as exhaust from the engine, and the air passing through the flues K,
space W, and conduit X, enters the furnace I, both water and air
increasing in temperature until the former reaches 1146 units.
As the advantage I gain by the introduction of hot air to the furnace
of the boiler, as stated, is decided, it is nevertheless small, and I shall
not refer to it as a very important feature in my improvements; suffice
it to say that it is enough to supply a sufficient amount of hot air to
support the most perfect degree of combustion of the fuel in the furnace
now attainable, and by reducing the temperature of feed water econo-
mize a portion of it, which would otherwise blow off through the safety

page_text: when employing the best feed water heaters now in use, which supply
feed water at a temperature of 212°.
Fourth. As a uniform temperature exists on all parts of the generator
B no liability of straining the latter occurs, which often takes place
when cold or comparatively cold feed water is injected.
In marine navigation the advantages of my Invention are eminently
apparent.
As I effect a very great saving in the amount of coal required for a
voyage I am enabled to devote to freight a corresponding proportion of
the carrying capacity of the vessel. I am also enabled to reduce the bulk
of the condense water apparatus or the fresh water supply tanks for the
reason that I require a less amount of new feed water than in other
engines in use with the exception of low-pressure condensing engines,
and as compared with these latter I stand about equal, that is to say,
the loss to be supplied in both is that due to imperfections and leaks of
the engine and apparatus.
A few comparisons will exhibit the gain in figures attaching to my
Invention:
Assuming in all that the engine is on the high pressure principle, and
is perfect, and is to be run with a pressure of 60 pounds of steam, the
feed water from the original source being of a temperature of 32°, and
it being understood that the water within the boiler at a vaporizing or
steam point contains 1176 units or degrees of heat Fahrenheit, and that
the back pressure upon the cylinder is one pound, except in the case of
the engine exhausting directly into the atmosphere, it being also under-
stood that the amount of heat required to convert water into steam
varies with the pressure, and that under one pound pressure 1148 units
of heat are required.
If the engine exhaust directly into the atmosphere with no provision
for heating feed water above the assumed temperature of 32°, 1110 units
of heat which were imparted to feed water are carried off by each pound
of exhaust steam, thus utilizing in the engine but about three per cent.
of the heat imparted to the water by the combustion of the fuel.
If a good feed water heater is employed the exhaust steam passing
through it will raise the temperature of the water as it is delivered to

page_text: the boiler to 212. Subtract 212 from 1176, and we have 964 units of
heat wasted.
By my method of heating the feed water, in which it is heated in a
closed space and is condensed without access to the atmosphere; I raiso
its temperature and deliver it to the boiler with 1148 units of heat, thus
utilizing or wasting by the engine but 28 units, and utilizing the
difference between this 28 units and 1176, which is 1148.
As before premised I also effect a considerable saving in consumption
of water, as none is lost except by leakage, etc., incident to all engines.
The figures given in the first two instances are taken from the highest
authorities as the best results yet attained, and my own figures are given
from careful practical tests.
As before premised I effect a considerable saving in the consumption
of water, for the reason that as I condense my exhaust steam in a space
closed to the atmosphere (but not in a vacuum) the only loss in the
original supply of water is that resulting from leakage and imperfections
of all steam apparatus, waste of test cocks, etc.
It may become desirable in many localities to economize strictly the
water used in generating steam, and to effect this I employ a cistern ď
located at a point near the pump Q, and connected by a pipe e³ with the
blow-off or outlet of the safety valve of the heater H.
The vapor
issuing from the said safety valve flows into the pipe e² and discharge
its condense water into the cistern d², where it accumulates until the
latter is partially or entirely full. To return this condense water to the
heater H I connect the cistern d² with the pump pipe T by a draft pipe a²,
and I connect the discharge pipe V of the pump with the interior of the
heater H by a pipe 63. I place a cock 3 in the pipe a², a cock 1 in the
draft pipe T, a cock 4 in the pipe 6*, and a cock 2 in the pipe V between
the pipe 6' and the boiler B.
When the tank & is to be emptied the cocks 1 and 2 are to be closed
and cocks 3 and 4 opened. The pump is now closed against drawing
water from the vessel H and discharging it into the boiler, and draws
water from the cistern & through the pipe a², and discharges it into the
vessel H through the pipe b³.
When the operation of emptying the cistern d' is completed, which
may perhaps occur once a day, or may be much less often, according to