Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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This invention relates to humidifiers of the type in which
two or more electrodes are mounted in a water container.
BACKGROUND OF THE INVENTION
In this type of humidifier, the electrodes are usually made
of rolls or tubes of wire mesh material but they may be made of other
conductive materials in the form of sheets, plates or rods~ In a
single phase humidifier there are two spaced electrodes for
connection to a single phase a.c.power supply but there may be three
or more electrodes in a polyphase system. When current is caused to
flow between the electrodes through water contained in the container,
the water is heated and subsequently boils, giving off the desired
steam. The amount of heating current that will flow depends upon the
electrical conductivity of the water9 the proportion of the
electrodes, actually immersed in the water and the spacing between
the electrodes.
It is known that the heating current can be reduced by
effectively lengthening the current path between electrodes, this
being effected by inserting vertical insulating material shields or
baffles in the space between the or each pair of electrodes. The
current instead of flowing directly between the electrodes, is then
forced to pass along a more indirect path around the edges of the
baffles. See for example Canadian Patent No. 518,972 of Head issued
November ~9, 1955. This has been found to be an extremely useful way
of compensating for an electrode voltage higher than that for which
the humidifier was designed. For example~ when humidifiers
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manufactured in Europe where the three phase supply is 380 volts are used
in Canada where the three phase industrial supply is 600 volts, approximately
the same design current can be ob~ained by using a baffle, given the same
degree of electrode immersion and conductivity of the contained water.
In addition i~ is known that electrode life in such humidifiers can
be extended by using larger electrodes because of their greater surface, and
hence mineral collecting, area. In a normal arrangement of such electrodes
however, current flow can become excessive at the design electrode water
immersion level and designed contained water conductivity at a given voltage.
Use of such vertical baffles between these larger electrodes provides current
flow control and thus extends the effective electrode life.
A problem which has been encountered with such baffles has been that
current flowing between the electrodes, in seeking the shortest path, may
be caused to flow below the baffles between lower ends of the electrodes
instead of around the edges of the baffles. This is primarily the case in
humidifiers which have a water filter protruding upwardly from the bottom of
the container around the water inlet/outlet. This shortened current path
counters the effect of the vertical baffles.
According to the present invention, this problem is obviated or
mitigated by providing an electrode humidifier water container comprising a
steam outlet at the top and ~ water inlet/outlet at the bottom, the container
being made of electrically insulating material or being coated internally
with electrically insulating material; at least two electrodes secured in
the container in spaced relation to each other; and, secured in the container,
non-enclosing shield means for the electrodes, the shield means being made
of electrically insulating material or coated with electrically insulating
material and having a first portion positioned between the electrodes so as
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to lengthen the current path between the electrodes and having a second por-
tion positioned beneath lower ends of the electrodes, normal to the first
portion and of a size and shape so as to lengthen further the current path
between the lower ends of the electrodes.
BRIEF DESCRIPTION OF THE DRAWINGS
.
These and other objects and advantages of the present invention will
become apparent upon reading the following detailed description and upon
referring to the drawings in which:
- Figure 1 is a vertical sectional schematic view of an example embodi-
ment of water container of an electrode humidifier according to the invention;
Figure 2 is a sectional view of the water container taken on line
II-II of Figure l;
Figure 3 is a vertical sectional view of the water container taken
on line III-III of Figure 2; and
Figure 4 is a sectional view corresponding to that of Figure 2 but
of a further embodiment of the invention.
While the invention will be described in connection with example
embodiments~ it will be understood that it is not intended to limit the
invention to such embodiments. On the contrary, it is intended to cover all
alternatives, modifications and equivalents as may be included within the
spirit and scope of the invention as defined by the appended claims.
DEIAILED DESCRIPTION OF T~IE INVENTION
In ~he drawings, similar features have been given similar
reference numerals.
Referring to Figures I and 2, the electrode hum;difier
water container 2 comprises a vessel made of a synthetic plastics
material. The container is provided with a water inlet 4 and a steam
outlet 6 (Figure 1). Electrodes 10 and 12, formed ~or example as a
wire mesh tube, are secured at spaced locations as indicated, within
container 2. These electrodes are provided with electrical contacts
13 for connecting to an appropriate a.c. supply. In operation, a
steam hose would be connected to outlet 6 to convey generated steam
away from the container and a combined water inlet and drainpipe
would be connected to water inlet 4. As illustrated in Figure 1, an
inverted "basket" type of filter 14 may be secured to the inside
surface of the bottom end of container 2 over water inlet 4.
An insulatiny shield or "baffle" 16 is secured in position
within container 2 as illustrated. Baffle 16 is preferable made of a
synthetic plastics material and comprises a flat, rectangular sheet
portion 18 mounted in vertical orientation and a disc-shaped portion
20 secured thereto, as by plastic welding or formed integrally with
vertical baffle portion 18. The width of vertical baffle portion 18
may be the same as the diameter of horizontal baffle portion 20, or
it may be slightly greater or less than that diameter. Baffle
portion 18 is preferable mounted centrally between the electrodes
within container 2.
In operation, with electrodes 10 and 12 connected to an
a.c. power supply, and with water in the container 2 immersing all or part
of the electrodes, current passes between electrodes 10 and 12 through the
water. Because of the presence of vertical baffle portion 18, current cannot
pass in a straight line between the electrodes, but must pass around the
longitudinal edges of vertical baffle shield 1~ along path 30 (Figure 2).
In this way the heating current passing between the electrodes has a greater
path. Because of the presence of horizontal baffle portion 20, a potential,
more direct current path 32 between the lower ends of electrodes 10 and 12
(Figure 1), around the lower end of vertical baffle portion 18, is blocked.
Instead, that current must follow the shortest current path 30 (Figure 2)
which path is designed, by the size and positioning of baffle 16, to be
shorter than path 34 below horizontal baffle 20. Horizontal baffle 20 has
the additional advantagc of providing a means to catch shale or other depo-
sits which may build up and from time to time fall off the electrodes and
vertical baffle portion 18 and block filter 14.
In Figure 4 there is shown schematically an alternative embodiment
of the present invention, particularly adapted for use with a three phase
system. In such a system there are three (or more) electrodes 40, 41 and
42 radially spaced 120 apart from each other about the center of container
2, the electrodes being adapted for connection to each of the three phases
of a three phase power supply. As there are three ~or more) electrodes,
the configuration of vertical baffle portion 45 differs. The disc-shaped
horizontal baffle portion 20 is essentially unchanged; but instead of a
single rectangular vertical baffle portion 18, three (or more) rectangular
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portions 45 are provided. The rectangular portions may be secured at
120 locations to a central elongated hub portion 48~ for example,
by push fitting longitudinal edges of baffle portions 45 into
resilient slots 49 provided in the hub. Alternatively the vertical
and horizontal baffle portions may be, for example, integral
constructions. As illustrated, each vertical baffle portion 45 may
be located much nearer one of the electrodes than the other of the
pair. As before, straight current paths between the electrodes are
prevented by the rectangular portions of vertical baffle portion 45
and also, as before, short circuit paths between the lower ends of
the electrodes are prevented by disc-shaped baffle portion 20.
It should be noted that vertical baffle portions 45 do not
extend radially outwardly as far as the inner wall of container 2.
It is envisaged that rectangular vertical baffle portions
18 or 45 may be provided with several through-apertures to assist in
regulating the shielding effect and hence the contained water level
and conductivity. Normally no such apertures would be provided on
disc-shaped horizontal baffle portion 20.
Thus there has been provided in accordance with the
invention a electrode humidifier that fully satisfies the objects,
aims and advantages set forth above. While the invention has been
described in conjunction with specific embodiments thereof, it is
evident that many alternatives, modifications and variations will be
apparent to those skilled in the art in light of the foregoing
description. Accordingly, it is intended to embrace all such
alternatives, modifications and variations as fall within the spirit
and broad scope of the appended claims.
