Note: Descriptions are shown in the official language in which they were submitted.
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SYSTE:M FOR GENERATING l~ICROBUBBLES IN A LIQ.UID ~ASS
S P E C I F I C A T I O N
OBJECT OF '1'~; INV~TION
The invention relates to a system desi~ned to homogenize a
liquid mass by injecting air bubbles into the actual liquid mass,
thereby to disturb the same and attain a uni~orm homogeneity
thereof. The system can be applied to electrolytic processes, gas
transfers, water purification, fish farms and so forth.
BACRGROUND OF TH~ INVE~TION
In electrolytic processes, the parts are anodized in a
horizontal arrangement because of the scarce height of the tanks
(usually between 2 and 3 m). Thus, the upward travel of the
bubbles injected into the electrolyte barely takes enough time
for them to come together before reaching the surface, and
therefore the methods used in injecting air bubbles can be deemed
to be acceptable.
With the introduction in anodizing processes of tanks having
a greater height ~between 6 and 7 m), the anodizing process is
carried out with the parts in a vertical arrangement, which means
that the systems usually employed to inject air into the
electrolyte are no longer valid, inasmuch as the bubbles produced
gradually come together as they travel up the approximately 6 or
7 m and, becoming increasingly larger, and preventing not only
homogenization of the electrolyte and correct anodizing, but
correct uniformity of the conductivity of the actual electrolyte.
In short, the effect sought by injecting bubbles is for the
latter to have as small a diameter as possible and the least
possible kinetic energy, viz. the lowest possible speed, so that
the bubbles remain unaltered as they travel up the tank,
preventing as best as possible th~ir coming together.
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Habitually, the mean5 used to produce bubbles comprised
making manifold orifices along the piping, which orifices had a
diameter ranging between 1 and 3 mm, thus being unduly large. An
attempt was made at overcoming this disadvantage by using porous
diffusers able to produce bubbles with a diameter of just a few
microns. That is to say, slow-moving small bubbles favour the
homogenization of the gas in a li~uid.
~ o such end, Spanish patent of invention 90010g3 claims a
homogenization device using a pDrous diffuser, such device
comprising a gas distributing element in which various injectors
are inserted through which the high-speed gas moves, the porous
elements or diffusers being prec.isely arranged to cover the
injectors, all such that on injecting the gas into the said
diffusers, the said gas may spread throughout the porous mass,
and the speed lowered to suitable circulation values through the
pores. On exiting through the diffusers, the gas produces bubbles
that are evenly spread throughout the surface of the diffusers
and evenly transferred and homogenized in the liquid mass.
Now then, the difficulties of using porous diffusers lies
in that when air or liquid ceases to be b~own through the same,
water enters through the said ceramic diffusers, filling the
inside of the piping, such that within a short space of time the
said porous parts will actually be clogged, thereby preventing
bubble production.
Furthermore, in the installations used habitually, the
branches making up the ducts where the porous diffusers are
arranged are mounted in series and therefore the loss of head is
important, prevents the last diffusers in each branch to evacuate
the water passed through the same, this leading on the one hand
to the placing of check valves preventing the entry of water into
the ducting when blowing stops, and on the other, in order for
blowing at the last diffusers on each branch to be appropriate,
to a larger quantity of air being blown which causes the first
diffusers in the branches to inject more air than should be.
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Finally, another disadvantage of the facilities that are
currently used, employing porous elements, could be said to be
that the failure of one of these porous parts leads the whole
process to be imbalanced, since all the installation's blowing
air leaks through the same.
Reference should also be made to US patents numbers
4,118,~47 and 4,048,072, the first of which claims an apparatus
for aerating a liquid mass having a lower hollow tube provided
with a ballast, which tube has orifices which lead on the one
hand into an air inlet and on the other into a chamber defined
between such tube and an sxternal porous tuhe, in order ~or the
bubbles to exit through the latter.
This patent of invention 4,118,447 is primarily conceived
to oxygenate fish farm or reservoir waters, such that although
the it is aimed at achieving bubbles of tiny calibre, clearly
being designed to oxygenate fish farms or the like, whether the
bubbles achieved are big or small is not all that important.
For its part, patent 4,048,072, that is designed for this
same purpose, provides that the bubbles exit through an
enveloping chamber lying between an external lattice and an
internal concentric tube, such chamber being full of a grained
product, such as pebbles.
In either patent, when air or gas is injected into the
device or diffuser provided, the pressure at which this is
effected must be the normal working pressure, in order for the
air to move the water that shall have flooded the inside of the
diffuser, which must naturally be immersed in a liquid medi~m,
but will do so at the sector close to the air inlet up to
wherever the injected air pressure is equal to the internal water
pressure, which means that bubbles will only exit through a
sector close to the entrance to the di~fuser rather than through
the whole of the ~ame. Now then, at an ingoing pressure in excess
of the working pressure it will be possible to cause the liquid
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inside the diffuser to move, but it will never be possible to
prevent the bubble leaving through the sector close to the air
inlet from being oversized and carrying more kinetic energy, such
kinetic energy causing the same to come together and hence to
become even bigger. In short, these patents 4,118,447 and
4,048,072, cited as background, cannot afford microbubbles, with
little kinetic energy, and it will therefore be impossible to
prevent the said kinetic energy from being absorbed when they
come together, whence the formation of oversize bubbles will not
be prevented.
In short, both these US patents are able to homogenize a gas
or air in the liquid or water, but are unable to provide high
quality homogenization for want of sufficient dispersion that
could be appropriate if they were appliad to certain processes,
namely electrolytic processes. These processes require the size
of the bubbles to be as little as possible and equal at different
depth levels, and at the same time a perfectly uniform
distribution of the microbubbles throughout the mass. All of this
is aimed at achieving a uniform distribution of the current,
modifying the conductivity of the electrolyte as little as
possible, and homogenizing the temperature thereof as much as
possible. These characteristics are not attained with the devices
or diffusers claimed in these patents 4,118,447 and 4,048,072,
inasmuch as the diffusers claimed in the same ~o not yield
microbubbles in the actual li~uid, and furthermore upward travel
is not slow, given the general configuration of the diffuser.
DESCRIPTION OF THE INVENTION
- The system subject hereof has been designed to fully solve the above problems, affording in such respect a simple and
efficient solution, relying in the first place on the fact that
the installation will be structured with lattices rather than
arranging the branches in series as in conventional
installations, the said lattice arrangement being such that the
porous diffusers are arranged in parallel thereby to avoid the
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oblems posed by the above-mentioned series arrangement.
It has also been provided that the air will not exit
directly through the porous diffusers, as is usually the case,
and thus before reaching such porous diffusers, the air shall
pass through a number of orifices provided in a concentric tube
in the porous diffuser, which orifices lead into a common
ducting, before reaching the actual porous diffuser, to equalize
the pressures. These concentric tubes naturally define a chamber
that can never be filled with liquid, moreov~r ensuring a uniform
air pressure.
On the other hand, the said concentric tube orifices linking
the chamber defined in the tube with the common chamker provided
before reaching the porous diffuser, are specifically arranged
on the lower sector, thereby for the useful surface through which
the bubbles exit to be located on the upper half of the porous
diffuser, whereas approximately the lower half remains as a
useless surface through which no bubbles will exit, this causing
the said bubbles to rise through the liquid mass up to the
latter's surface without coming together.
The section of the orifices on each main branch has also
been provided to be greater than the sum of the surface of the
above-mentioned calibrated ox outlet orifices in order to cause
overpressures in the conduits thereby to achieve a correct outlet
of the air.
In conse~uence of the lattice arrangement of the various
branches in the installation, the failure of a diffuser will not
affect the rest of the network, inasmuch as these porous
diffusers afford no resistance whatsoever to the passage of air,
and therefore the slight head loss at the outlet would only be
influenced by the calibrated lower orifices of the concentric
tube provided in the porous diffusers, which tube will further
comprise a plastic or like material and will not break.
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It finally remains to be said that clogging of the said
di~fusers comes about when water enters through the diffuser up
to the lower orifices, so that since the latter are very small
and the through speed is very low, the clogged section will be
the lower diffuser sector, viz. the useless sector in bubble
production.
It shall have become clear hitherto in the description that
the arrangement of the porous diEfusers in parallel, forming
lattices, resembles an electric layout where resistance is
similar to charge loss, and therefore total charge loss will be
equivalent to an element divided by the nuymber of elements, and
hence blowing pressure of the equipment compared with voltage for
a same air passage, must be the lower blowing pressure.
DFSCRIPTION OF THE DRAWINGS
In order to provide a fuller description and contribute to
the complete understanding of the characteristics of this
invention, a set of drawings is attached to the specification
which, while purely illustrative and not fully comprehensive~
shows the following:
Figure 1.- Is a diagrammatic view of the lattice arxangem~nt
of the porous diffusers provided in a conventional plant for
homogenization of a liquid mass.
Figure 2.- Is a cross-section perspective view of the lower
half of a porous diffuser including the concentric tube provided
with the calibrated orifices in the lower part thereof and
leading into a common chamber.
Figure 3.- Is finally yet another cross-section in outline
of what could be said to be the useful surface and useless
surface of the porous diffuser for the outlet of bubbles.
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~EEERRED ENBODIMENT OF 1~ INVENTION
These figures, and referring firstly to figure 1, show part
of a general installation forming a lattice with branches (1) or
fluid distribution conduits, with the porous diffusers (2)
arranged in parallel, and the relevant communication orifices (3)
provided on the main branches (1).
Figure 2 shows a cross-section of a porous diffuser (2),
such comprising a tubular body (4), obviously made of porous
material, inside which is concentrically arranged a tube (5)
preferably made of plastic, such as PVC, the lvwer part of which
is provided with a number of calibrated orifices (6) leading into
a common and linear chamber (7) before reaching the actual body
(4) of the general porous diffuser (2). The section of the
orifices on each main branch must be greater than khe sum of ths
surface of the outlet orifices ~6) in order to cause
overpressures in the conduits and for outlet of the air to be
correct.
According to this structure, the air entering the chamber
formed by the concentric tube (5) reaches the latter's orifices
(6) and before arriving at the porous body or diffuser (4) enters
a linear and common chamber (7) that, as aforesaid, joins all the
orifices (6), thereby for the pressures to be equalized.
Since the air has little speed as it exits through the
diffuser (4~, distribution shall take place at the upper surface
enclosed by the arch (8~ in figure 3, whereas the lower surface
enclosed by the arch (9) is a ussless surface through which no
bubbles shall exit, thereby to prevent the bubbles that could
exit through the lower part from slipping over the lower contour
of the actual diffuser and the said bubbles from coming together,
which would obviously lead to a total lack of homogenization of
the liquid mass.
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Therefore, based upon the said dif~user, when immerse~ ~h$~ 3
a liquid, the latter shall pass into the tube (5) through the
lower sector, this being where the orifices (7) are provided,
until it reaches a certain height, which i6 when the pressures
of the air or gas lying inside the actual tube (5) and of the
water or liquid flooding the diffuser shall be balanced, and
therefore the latter shall never be fully flooded, as compared
with the diffusers described in the US patents referred to as
state of the art.
We feel that the device has now been sufficiently described
for any expert in the art to have grasped the full scope of the
invention and the advantages it offers.
The materials, shape, size and layout of the slements may
be altered provided that this entails no modification of the
essential features of the invention.
The terms used to describe the invention herein should be
taken to have a broad rather than a restrictive meaning.
