IMPROVEMENTS IN APPARATUS FOR THE CONDENSATION OF STEAM IN STEAM ENGINES
Year: 1862

page_text: PROVISIONAL SPECIFICATION left by Zerah Colburn at the Office of
the Commissioners of Patents, with his Petition, on the 23rd July
1862.
I, ZERAH COLDURN, of Number 15, Tavistock Street, Bedford Square, in the
County of Middlesex, Mechanical Engineer, do hereby declare the nature of
the said. Invention for "IMPROVEMENTS IN APPARATUS FOR THE CONDENSATION OF
STEAM IN STEAM ENGINES," to be as follows:-
The air pump as ordinarily used in condensing steam engines performs two
distinct purposes, the first of which is the removal from the lower part of the
condenser of the condensed steam and injection water constantly collecting
there, while the second purpose is the removal of air brought in with the
injection water, and to some extent introduced through slight leaks in the
condensing apparatus itself. Now I dispenso with the air pump, and accom-
plish its two purposes in the following manner :-Wherever I can obtain a
clear fall of not less than thirty feet, or, which is better, thirty-three feet below
the lowest part of the condenser, I allow the injection water and condensed
steam in the condenser to run off by their own gravity, and in opposition to the
external pressure of the atmosphere, the overflow or discharge pipe through
which they descend having its lower or discharging end kept constantly under
water, so that no air may enter it, and thus gain access to the condenser.
This mode of keeping the condenser clear of water has been already occa-
sionally employed by engineers, but not in a manner to dispense with the air
pump.

page_text: Where I cannot obtain a clear fall of thirty feet from the condenser so as to
discharge the water by its own gravity and in opposition to the pressure of the
external atmosphere, I then employ a force pump, which I prefer should be a
centrifugal pump, to force out the water from the bottom of the condenser.
I will now show how I effect the removal from the condenser of the air
brought in with the injection water and the air also introduced through leaks
in the condensing apparatus itself. I employ for this purpose a vessel which
I call the hydraulic exhauster, and which vessel I place at a level somewhat
above that of the condenser. The hydraulic exhauster is a vessel so fitted with
valves that it may be first filled with water and any air within the vessel
be thus expelled at the same time through a self-acting valve, after which the
water in the exhauster may be emptied into the condenser or into a vessel
suspended within the condenser. The space which the water previously
occupied in the exhauster will then receive a share of whatever air may be
collected in the condenser, and in this manner the exhauster will perform the
purpose of the ordinary air pump in abstracting air from the condenser. The
communication between the exhauster and condenser being then closed by a
valve worked by the engine, and the exhauster being again filled with water,
and its contained air thereby expelled through a self-acting valve, it will repeat
the operation previously described, and by being constantly worked in the
manner herein-before explained, it will keep the condenser constantly free
from air, except at the very low tension at which air is generally present in all
good condensers.
The water admitted to and discharged from the hydraulic exhauster in the
manner described is afterwards used as injection water for condensing the
steam in the condenser, this steam being the exhaust steam of the engine, to
which the apparatus herein described is applied. When the lower valve of
the hydraulic exhauster is opened and held open by means of mechanism
worked by the engine, the water in the exhauster will fall through a pipe or
other suitable passage into an open topped vessel, suspended in the upper part
of the condenser. From this vessel the water will flow out through a suitablo
injection nozzle or pipe, either fitted or not fitted with what is called a "rose,"
and thus the water will run into the lower part of the condenser, condensing
the steam on its way. The open-topped vessel placed within the upper part of
the condenser may be of any form, but should be of sufficient capacity to
contain at least all the water which the hydraulic exhauster can dischargo at
one emptying. As the interior of the open-topped vessel, which may be called
the receiver, is always in free communication with the whole interior of the
condenser, it is evident that no temporary increase of pressure in the condenser

page_text: as from the sudden admission of a large volume of exhaust steam, can check
the flow of the injection water through the injection pipe in the bottom of the
open-topped vessel or receiver.
The valves of the hydraulic exhauster are to be of any simple kind suitable
for regulating the flow of liquids, and with the exception of the self-acting
valve for the escape of air from the exhauster during the admission of water,
are to be moved in any convenient manner by the engine. If they are moved
at such a rate that the exhauster is filled once and emptied once for every two
single strokes or one revolution of the engine, the capacity of the exhauster,
and that also of the open-topped receiver suspended in the upper part of the
condenser, should be each equal to about one-sixteenth the capacity of the
steam cylinder in ordinary condensing engines. The capacity of the exhauster
must be such that it will always supply the greatest quantity of injection water
ever required, and when less is wanted blocks of wood of proper size may be
fixed within the exhauster to displace any quantity of water not required. The
exhauster must be so placed that while the water is entering it the water shall
be under the full pressure of the atmosphere, and under the further pressure
of at least a few inches in depth of water, so as to insure the ready filling of
the exhauster with water, and a correspondingly rapid expulsion of whatever
air the exhauster may contain.
Unless there is a clear fall of at least thirty feet from the condenser there
should be a self-closing valve, opening outwardly and placed in the passage
leading from the condenser to the centrifugal force pump, which would in
such case be employed for clearing the condenser of water. This valve being
closed when the engine is about to be started the condenser and hydraulic
exhauster are to be blown through in the manner now practised in starting
condensing engines. A jet of water being then turned into the condenser, and
the steam thereby condensed, the engine may be started, and as the force
pump begins to act it will force open the self-closing valve, and clear the
condenser of water. The condenser and bydraulic exhauster may be advan-
tageously placed within a tank of water, so that even if these parts be not
absolutely air-tight, no leakage of air into them will take place.
Inasmuch as in all steam engine condensers a certain amount of air at a
low tension is always present, and as the water in my hydraulic exhauster
would in its descent leave an almost perfect vacuum behind it or in the upper
part of the exhauster, it may be found in practice that even the highly
rarified air in the condenser is sufficient to oppose an appreciable obstacle to
the descent of the water from the exhauster. Therefore I should in some, if
not in all cases, provide a small additional pipe, which should open a com-

page_text: munication between the interior of the condenser and the uppermost part of
the exhauster, and to the upper end of this pipe I should apply a valve
connected to and moving simultaneously with the lower or discharge valve of
the exhauster, so that when the discharge valve rose to permit the passago of
the water from the exhauster to the condenser, the valve at the upper end
of the small pipe would also rise, and thereby open a free communication
between the space below and that above the falling water, so that the water
would fall freely or without obstruction of any kind.
In some cases it may be desirable to place the condenser and exhauster
soveral feet above the level of the steam cylinder of the engine, so as to obtain
a fall to take away the water used in the condensing and exhausting apparatus
by gravity. This would be especially advantageous where a natural supply of
water from a source above the thus elevated condenser could be readily com-
manded. It might even be judicious in some cases to employ a centrifugal
pump to forco the supply of water for condensing and exhausting up to such a
height that it would afterwards flow freely out of the condenser by gravity,
and in opposition to the pressure of the atmosphere. In the case of steam-
pumping engines pumping water up to or somewhat above the height to which
the condenser and exhauster might thus require to be elevated, it might be
found useful to take the water for condensing and exhausting direct from the
rising main. It is evident that two or more bydraulic exhausters may be
employed side by side and be filled and emptied alternately or simultaneously
into the condenser. So also the water for the hydraulic exhauster might be
discharged by itself into the water pond or reservoir, and the condenser be
separately supplied with injection water. This course, however, would not be
a preferable one.