Improvements in Means for the Purification of Water in Open Vessels.
Year: 1897

page_text: Date of Application, 12th Mar., 1897-Accepted, 21st Aug., 1897
COMPLETE SPECIFICATION.
Improvements in Means for the Purification of Water in Open
Vessels.
I, ALFRED DERVAUX, of 17 Rue Faidherbe Lille, in the Republic of France,
Engineer, do hereby declare the nature of this invention, and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement:
1
If calcareous water intended for an industrial purpose is purified by boiling it
with steam so as to turn the dissolved bicarbonate of lime into insoluble carbonate
of lime, which then precipitates, the process must be performed in a closed vessel
as it is otherwise too expensive in consequence of the loss of steam.
The use of closed vessels is, however, combined with considerable disadvantages,
in that the cleansing of such vessels is circumstantial, and, further violent
shocks arise within the latter during work; these shocks are also accompanied by a
loss of steam which if it shall be avoided necessitates special arrangements.
The object of my present invention is, first, to effect the purification of the water
in an open vessel, in such a way, that a loss of steam is practically avoided; and,
second, to regulate the process of purification by aid of the different densities (of
the water) resulting from the supply of water and steam into the open vessel.
I attain the said objects, first, by a méthod the particular feature of which
consists in letting the water to be purified form a current of a downward direction,
or leading it in this manner through the purifying-vessel respectively, the steam
for heating the water being caused to pass upwards within said vessel, and to con-
dense before arriving at the upper surface of the column of water contained in
the same. The second point of my invention relates to the apparatus, i.e., the
purifying-vessel, and consists in arranging within the same either a float or an
areometer adapted to regulate the supply of the water or the steam according to
the density of the mixture of water and steam present within the open vessel.
The mere introduction of steam into a stationary column of boiling water would
not answer the object of doing away with the loss of steam. What is necessary
is proportionating the quantities of water and steam in such measure that the
steam is perfectly condensed before arriving at the upper surface of the water.
If, thus, the open vessel should contain a stationary column of water, then the
heated lower part of the latter would soon rise to the surface, whereas the cool
upper part of the same would sink, so that the steam could escape, and would to a
great extent be lost. If, however, the water forms a current of a downward
direction, then the upper part of the water remains cool in consequence of the
sinking water being constantly replaced by fresh, and the complete condensation
of the steam occurs below the upper surface of the water. This is especially the
case if water and steam move in opposite directions, that is to say, if the steam
enters the vessel at the bottom and the water enters the same at the top, because in
this case any non-condensed remainder of the steam meets the cold water and is
energetically condensed thereby.

page_text: I have shown some forms of construction of the apparatus in Figures 1 to 4 of
the accompanying drawings, said figures showing the apparatus in vertical section,
all immaterial parts being purposely omitted.
The apparatus consists of a cylindrical vessel A, Figure 1, which communicates
at its top with the outer air, and contains a column of water, the water being intro-
duced into the vessel through a pipe B. The water when flowing downwards
within the vessel A meets a current of steam introduced into said vessel through
the pipe V.
The water is thus boiled under atmospheric pressure, and leaves the apparatus in
a purified state through a junction C, from which it passes over into a vertical
ascension or delivery-pipe S.
It is obvious that any escape of steam at the surface of the water is perfectly
prevented, because with a correct proportioning of the water and the steam the
latter is condensed by the cold water, before it (the steam) arrives at the surface
of the water.
When the water present within the ascension- or delivery-pipe S has ceased
boiling, it forms a column of a constant weight, which is in equilibrium with
the column of boiling water within the vessel A. The weight of this column of
water remains also constant but the height of the column would depend upon and
vary according to the density of the mixture of water and steam forming it.
This gives a means for regulating the process.
In the form of construction shown in Figure 1 there floats within the open
vessel A, an areometer G which is suspended from a lever a secured to the plug of
the water-valve b. The arrangement is such that when the areometer ascends,
the supply of water through the valve 6 decreases, and when the areometer descends
an increase of the said supply takes place. If, thus, the quantity of steam intro-
duced into the vessel A is too great, the density of the mixture of water and
steam will be reduced, the areometer will descend, and the supply of water through
the valve b will be increased until the normal density of the mixture has been
re-established. The absolute weight of the column of water in the vessel A
remains constantly the same by aid of the column of water in the ascension-
pipe S.
Instead of letting the areometer G act upon a water-valve as stated I may let it
act upon a steam-valve V¹ as represented in Fig. 2.
In this case the areometer acts in such a manner, that when ascending it causes
an increase in the supply of steam by an appropriate adjustment of the plug of
the valve V, the supply of steam, however being decreased when the areometer
descends. The effect attained by this form of construction is just the same as in
the form of construction first described. In order to prevent the areometer from
moving in jerks, as is peculiar with areometers, I prefer to arrange a spring d
between the lever a and a suitable support, as shown in Figures 1 & 2.
In Figure 3 I have shown a form of construction in which the regulation is
effected with aid of a float F, the latter actuating in this case the water-valve b.
The manner of operation is different from the form of construction shown in
Figure 1, in that on the supply of steam being too great, or, in other words, on
the water rising within the vessel A, the plug of the valve b is so turned that in
spite of the upper surface of the water being already rising, an increased supply of
water through the pipe B is effected. This increased supply results in the re-
establishment of the normal density of the mixture, and this re-establishment of
the normal density causes the upper surface of the water to reassume its normal
height.
In the form of construction represented in Figure 4 I have also made use of a
float F, but in this case the float acts upon the valve of the steam-pipe V. The
supply of steam is decreased when the surface of the water rises, and in the
reverse case the plug of the valve is turned in the other direction, so that then the
supply of steam is increased and, thus, the specific weight of the mixture is
1

page_text: In these forms of construction (Figures 3 & 4) ne spring d (Figures 1 & 2) may
be dispensed with, because the movement of the float is practically uniform.
I wish it to be understood that to maintain the constant weight of the mixture
in the vessel A may make use of a non-return valve with a constant load instead
of employing for that purpose the weight of the column of water in the delivery
pipe S.
Having now particularly described and ascertained the nature of my said in-
vention, and in what manner the same is to be performed, I declare that what I
claim is:
1
1. The method of purifying water, consisting in letting the water form a current
of a downward direction, leading steam into said water at the lower end of the
current, and regulating the supply of the water or of the steam in such a manner
that the steam condenses before arriving at the upper end of said current of water,
as set forth.
2. An apparatus for practizing the method afore claimed, consisting of an
upright vessel, a pipe for supplying water, another pipe for supplying steam, a
cock or valve inserted in one of said pipes, and an areometer located in said vessel,
and connected with said cock or valve, as set forth.
3. An apparatus for practizing the method afore claimed, consisting of an
upright vessel, a pipe for supplying water, another pipe for supplying steam, a
cock or valve inserted in one of said pipes, and a float located in said vessel, and
connected with said cock or valve, as set forth.
Dated this 12th day of Maren 1891.
By Geo. Thos. Hyde,
ALFRED DERVAUX.
1 Broad Street Buildings, London, E.C., Agent for the Applicant.