AN IMPROVED METHOD OF AND APPARATUS FOR DETERMINING THE QUANTITY OF WATER CARRIED MECHANICALLY BY STEAM."
Year: 1880

page_text: LETTERS PATENT to Charles Denton Abel, of No. 28, Southampton
Buildings, Chancery Lane, in the County of Middlesex, for an Invention
of "AN IMPROVED METHOD OF AND APPARATUS FOR DETERMINING THE
QUANTITY OF WATER CARRIED MECHANICALLY BY STEAM." A communi-
Ti An Runn of Danio Timanea
PROVISIONAL SPECIFICATION left by the said Charles Denton Abel at the
Office of the Commissioners of Patents on the 29th November 1880.
CHARLES DENTON ABEL, of No. 28, Southampton Buildings, Chancery Lane, in
the County of Middlesex. "AN IMPROVED METHOD OF AND APPARATUS FOR
DETERMINING THE QUANTITY OF WATER CARRIED MECHANICALLY BY STEAM."
[A communication from abroad by François Alexandre Brocq, of Paris, France.]
It is known that saturated steam or vapour in contact with its generating liquid
possesses for every degree of heat a maximum pressure that cannot be exceeded.
If therefore a recipient contains, at a certain constant temperature, a mixture of
steam and of water carried off, thereby the pressure of this mixture will be
constant even when the internal volume is increased. But as soon as, in con-
sequence of the increase of volume, the water carried with the steam is entirely
evaporated, any further increase of volume will produce a decrease of pressure,
because. the steam, being no longer saturated, will then obey the same laws as other
dry gases.
If therefore the moment of such decrease of pressure be accurately observed, the
quantity of water carried mechanically by steam of a given temperature and
pressure can be readily determined by the increase of volume necessary to produce
such decrease of pressure.
The ratio of the weight of water carried thereby to
that of the dry steam contained in the mixture will be the quotient of the increment
of volume divided by the known original volume of the mixture. In practically
applying this method of determining the quantity of water the following
construction of apparatus is employed:-A closed casing, provided with inlet

page_text: and outlet valves by which it communicates with the steam generator, contains
two recipients of determined volume having openings by which they communicate
with the interior of the casing which openings can be closed by slides, valves, or
cocks from the outside. Each recipient contains a plunger or piston that can be
made to travel therein by means of a screw spindle so as to increase or decrease
the volume of the recipient. Between the two recipients is a vessel divided into
two compartments which are filled with suitable liquid such as mercury, and have
each a flexible diaphragm subjected respectively to the steam pressure in one of
the recipients. The two compartments communicate with each other by a pipe
leading to the outside of the casing where a portion of the pipe is of glass, and
contains a moveable index, the tube being also filled with the mercury.
The mode of operating with this apparatus is as follows:-The steam from the
generator being in the first instance allowed to circulate through the casing and
through the recipients, the openings of the recipients are closed and the plunger or
So
piston of the one is moved by the screw spindle so as to increase its volume.
long as there is free water present the pressure in such recipient will remain the
same as that in the other recipient notwithstanding the increase of volume, but as
soon as the volume is increased to such an extent that the whole of the free water
is converted into steam, any increase of volume beyond that point will result in a
reduction of pressure in the recipient. In consequence hereof the excess of pressure
in the other recipient in acting on the diaphragm of the gauge will force a portion
of the mercury through the pipe into the other compartment, and in thus moving
the index will show that there is no more free water present. On now determining
the exact amount by which the volume of the recipient has been increased, which
can be easily done by observing the number of revolutions of the screw spindle,
the quantity of water carried by the steam can be readily calculated as above
described.
It will be evident that only one recipient might be employed, the diagram of
the one compartment of the pressure gauge being acted upon directly by the steam
in the casing itself, but it is preferable to employ two in order to insure uniformity
of temperature on both sides of the pressure gauge.
In place of the above described construction of pressure gauge any known
construction might be employed that will indicate differences of pressures existing
in two localities.
The above described method and apparatus may be employed with advantage
for regulating the superheating of steam as it enables the action of the superheater
to be so controlled that it will beat the steam only to the point of evaporation of
the whole of the free water.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Charles Denton Abel in the Great Seal Patent Office on the
21st June 1881.
CHARLES DENTON ABEL, of No. 28, Southampton Buildings, Chancery Lane, in
the County of Middlesex. "AN IMPROVED METHOD OF AND APPARATUS FOR
DETERMINING THE QUANTITY OF WATER CARRIED MECHANICALLY BY STEAM."
A communication from abroad by François Alexandre Brocq, of Paris, France.
This Invention is based on the known fact that steam, in contact with its
generating liquid, possesses for a certain degree of heat a definite pressure, the value
of which is entirely independent of the variation that the volume of steam mixed
with its liquid may be subjected to. It is well known what occurs during such
alterations of volume. An increase of volume produces the evaporation of a certain
quantity of liquid, and if the increase of capacity is sufficiently slow to enable the
heat necessary for the evaporation to be conveyed through the sides of the recipient
there will occur neither decrease of temperature nor of pressure. But if by a
sufficient increase of volume a point has been arrived at in which the steam exists
at a pressure corresponding to its temperature without excess of liquid then any
further increase of volume will cause a decrease of pressure. If now we consider
the amount of increase of volume requisite for producing a certain decrease of
pressure it will evidently be found to be equal to the volume of the steam produced
by the water carried by the mixture, at the pressure and temperature of the latter.
Thus, it being desired to find the ratio between the weight of the water and that of
the saturated steam by which it is carried, this will be readily given by the ratio
between the volume of the unexpanded saturated steam and that of the steam.
expanded to the point at which there is no more excess of water, the temperature
and pressure of the two volumes being the same.
The operation, according to the present Invention, therefore consists in taking a
definite known volume of the mixture of steam and water, and increasing its volume
with suitable speed until a decrease of pressure shows itself, whereupon by.
determining the proportion between the two volumes the proportion of water
contained in the original saturated steam will be ascertained.
This method of operating, on which is based the present Invention for ascertaining
the quantity of water carried mechanically by steam, can be practically carried out
by means of various arrangements of apparatus. The accompanying Drawing
shews the arrangement employed by preference, with a view to, enabling the
measurement to be easily effected.
Fig. 1 shews a side elevation; Fig. 2, a plan; Fig. 3, a longitudinal section; and
Fig. 4, a sectional plan; Figs. 5 and 6 shew cross sections taken respectively on
lines M, N, and P, Q.
X is a cast iron chamber which the steam from the boiler enters through an
opening at A, and whence it issues through the opening B. On its upper side the
chamber has a large rectangular opening closed by means of a plate D secured by
screws b, b. To an inner edge a, b, Fig. 5, is bolted a second cylindrical vessel E
of gun metal, which.constitutes the recipient of known volume in which, at any
desired time, may be imprisoned a quantity of the mixture of steam and water to
be tested. The axis of this recipient corresponds with that of the opening A, and
it has facing this opening a vertical rectangular aperture T equal in height to the
A similar aperture formed
diameter of A, and a width shewn on plan, Fig. 4.
at T at the lower side of the recipient E. These two apertures, can be simul-
taneously opened and closed by means of slides F, F', worked externally by means
of the handle C and rod t. The necessity for simultaneously closing the apertures

page_text: will be readily understood. If the outlet aperture T were closed first a certain
amount of compression would take place in the steam in the vessel E, while if the
inlet T were closed first the steam would be slightly expanded, so that in neither
case would the enclosed steam be identical with that contained in the surrounding
chamber X. The recipient E has two other holes; a circular one at P through
which passes a plunger G, and which is provided with a stuffing box, and another
at M, Fig. 3, which is also circular, and is enclosed by a boss H fixed or formed on
the chamber E. Covering the aperture M is a circularly corrugated disc m of
German silver, constituting the sensitive membrane of a pressure gauge, to be
presently described. The plunger G entering the recipient E.through the stuffing
box is a cylindrical tube closed at its inner end, and carrying at its outer end a nut
or female screw thread e into which screws the screw spindle V, which is of steel,
and passes through the stuffing box R of the vessel X, in which it is held against
longitudinal motion by a collar f, so that on rotating the screw by means of the
hand wheel k, which is secured on its square end g by a nut h, the plunger G
is caused to move outwards, thereby increasing the volume contained in the
recipient E. The volume of the plunger being accurately determined, as is also
the extent to which it is withdrawn from E by each rotation of the screw, the
threads of which are made accurately uniform for this purpose, it follows that the
increase of volume of the recipient E for each rotation of the screw spindle will
also be accurately given. The boss H, covering the membrane m, is formed so as to
present a concave space above the latter, and it has passages i, l, formed in it
communicating at one end with the interior of the recipient E, and at the other
end with channels formed in the sides of a conical tap n fitted therein, so that
when this tap is turned into the position shewn, the said passages establish a
communication between the interior of the recipient E and the space above the
membrane, thereby establishing an equilibrium of pressure on each side of the
latter, while when the tap is turned 90 degrees this communication is cut off. The
stem of the tap n passes through a stuffing box on the cover D, and has a handle o
by which it is turned. The stem and tap have a longitudinal hole lined with a
glass tube through which passes the insulated screw p, which can be screwed by
the head 9 so as to touch the membrane m with its inner end. The screw being
put in electrical communication with the one terminal of an electric circuit, while
the membrane is put in communication with the other, it follows that when the
screw touches the membrane the circuit is closed, and the current will effect the
ringing of a bell included in the circuit, while the slightest motion of the membrane
away from the screw will break the contact and stop the bell.
The mode of operating with the apparatus is as follows:-Steam being allowed
to flow through the chamber X on its way from the boiler, and the apertures T, T,
of the recipient E being open in the first instance, so that the steam also freely
passes through the latter, the slides F, F', are simultaneously closed so as to enclose
a certain volume of the saturated steam in the vessel E. The tap n is then turned
so as to close the communication between the upper side of the membrane m and
the interior of E, and the screw p is screwed inwards until it touches the membrane,
whereby the electric bell will be set ringing. The screw spindle V is now turned
so as to move the plunger G outwards, thereby increasing the volume in E occupied
by the steam. According to what has been above stated so long as free water
contained in the steam this increase of volume will not cause any decrease of
pressure, the temperature being maintained by conduction from the steam in the
outer chamber, and consequently the equilibrium above and below the membrane
will be maintained, and the bell will consequently continue ringing, but as soon as
the point is reached at which there is no more free water in the steam there will
be a decrease of pressure in the chamber E, and the slight excess of pressure
existing above the membrane produced when this point is reached will, in depressing
the membrane, break the electrical contact, and cause the bell to cease ringing.
As the slightest possible difference of pressure will bring about this effect it will be
seen that practically the ceasing of the bell will indicate the moment when, by the

page_text: increase of voluine the whole of the free water has been evaporated, and conse-
quently on now ascertaining by the number of revolutions that have been given to
the screw the exact increase that has taken place in the volume of the steam, and
hence also the proportion of such increase to the original volume, the quantity of
water originally carried by the steam can be determined.
Any ordinary form of pressure gauge would not be suitable for the above purpose,
as it would not indicate with sufficient sensitiveness the necessarily exceedingly
small difference of pressure that takes place in the above operation, in as much as
the indication must be given at the moment the equilibrium on each side of the
membrane ceases in order for the measurement to be accurate.
Having thus described the nature of the said Invention, and in what manner the
same is to be performed, as communicated to me by my foreign correspondent, I
claim,―
First. The method herein described of determining the quantity of water carried
mechanically by steam by measuring the amount by which the volume of the
steam can be increased under a constant temperature without diminishing its
pressure.
Second. The use of apparatus for determining the quantity of water carried
mechanically by steam, consisting of a recipient enclosed in a chamber through
which the steam passes freely, which recipient has, firstly, a plunger, piston, or
diaphragm, by which its volume can be increased; secondly, apertures provided
with slides, by which the communication between the recipient and the surrounding
chamber can be cut off; and, thirdly, a sensitive indicating apparatus for shewing
a very small decrease of pressure in the recipient, substantially as herein described
with reference to the accompanying Drawings.
In witness whereof, I, the said Charles Denton Abel, have hereunto set my
hand and seal, this Twenty first day of June, in the year of our Lord
One thousand eight hundred and eighty one.
CHAº. D. ABEL. (L.S.)