Background of the invention
[0001] The present invention relates to the field of the chemical technology and more in
particular to the field of the electrochemical processes as it relates to a particular
membrane electrolytic cell characterized by the presence of a stagnation chamber.
The device is used in preparing, starting from aqueous solutions with low concentrations
of dissolved salts, metastable, oxidizing or reducing substances, to be used in technological
processes as replacement of chemically stable reagents.
State of art
[0002] The Japanese patent application Nr.
JPS57194273 describes an electrode for producing hydrogen, with low voltage, by means of arranging
cation exchange membrane between the anode and the cathode of an electrolytic cell
also including porous septa without electrolytic activity not in direct contact with
the electrodes.
[0003] The German patent application Nr.
DE102011053142 describes an electrolytic cell to produce hydrogen and oxygen from the electrolytic
decomposition of water which comprises a housing, electrodes, connected at the poles
to a current source, and separated from one another by a membrane which divides into
two the electrolytic cell, above the electrolytic cell there is a gas separation chamber,
which is useful to separate oxygen and hydrogen from the gas-liquid mixture, and another
chamber including a drop separator above the gas separation chamber for the additional
purification of water or oxygen. The different chambers are arranged vertically and
separated by horizontal partition walls having pores allowing the passage of the liquid-gas
mixture and the liquid dropping. The outlet routes of the produced pure hydrogen and
oxygen gases lie on the upper cover, on the contrary the inlet and outlet routes for
water and electrolysis liquid lie on the lower wall of the cell. Even an additional
drop separator could be present, containing catalytic material for an additional purification
of water or oxygen, flowing vertically. In the housing, the membrane is arranged at
a height so as to obtain a defined distance between the upper portion of the electrolysis
chambers and the electrode, and even the electrolysis chambers are separated by membrane
walls. The drop separator can include as catalytic material fibres or nickel wires
or other catalysing supports such as fibres or ceramic porous bodies. A perforated
plate with openings is placed on one side of the anode and/or of the cathode, which
has a locking cursor, perforated too and mobile with respect to the perforated plate.
An insulating layer and/or a surface heating element is applied to the electrode at
the level of the through holes. A membrane filter is placed in the inlet holes of
the liquid-gas mixture and the membrane allows the passage of the produced gaseous
oxygen and hydrogen and keeps the liquid portion of the mixture.
[0004] The European patent application Nr.
EP0922788 describes an electrochemical device for the gas production from aqueous solutions,
constituted by two vertical and coaxial cylindrical electrodes arranged between the
two bushings characterized by a structure and an arrangement which allows a helical-like
motion of the electrolytes inside the electrolytic chambers. This is determined by
the presence of tilted channels and helical-like guiding elements in the bushings.
In particular the starting solution enters on the lower side and through the helical-like
guiding elements moves in the electrolytical chambers towards the upper portion wherein
the products outgo through the tilted channels of the upper bushing. In this way the
ejection of the liquid and gaseous products is facilitated and it is avoided that
a gas stopping area in the electrolytic chambers is formed.
[0005] The herein described devices known in the art are devised with the purpose of purifying
and collecting the gaseous products, hydrogen and/or oxygen, obtained by means of
the electrochemical devices starting from liquid-gas mixtures.
[0006] In the devices known in the art, in the upper portion of the cathode chamber gaseous
areas, mainly made of H
2, are formed, which if they are not timely removed, lead to considerable energy losses
and determine a decrease in the process yield.
[0007] With the purpose of solving the above-mentioned technical problem an electrolytical
device was developed, for preparing metastable, oxidizing or reducing substance, starting
from aqueous solutions with low concentrations of dissolved salts, which avoids gaseous
stagnations so as to determine good yields of the process and a high energy saving.
Object of the invention
[0008] The above-mentioned technical problem is solved by providing the electrochemical
device of the present invention comprising two electrodes, a first electrode with
tubular shape and circular section, which is the cathode, and a second electrode with
tubular shape and circular section too, acting as anode, the latter is arranged inside
the cathode and it is coaxial thereto. The two electrodes limit a space divided into
two chambers by a membrane wall concentric to the first electrode, the two chambers
are the cathode chamber, between the first electrode and the membrane, and the anode
chamber, between the second electrode and the membrane wall. The device then has two
sealing bushings, arranged at the ends of the two electrodes, wherein the lower bushing
has inlet channels of the electrolytes both to the cathode chamber and to the anode
chamber, whereas the upper bushing has the outlet channels of the electrolytes from
these chambers. Said device at the intersection between the cathode chamber and the
outlet channel of the electrolytes from the cathode chamber, has a stagnation chamber
with spheroidal shape opened to the cathode chamber and connected to the outlet channel
of the electrolytes from the cathode chamber by a connector pipe. The elements constituting
the device have particular geometrical sizes.
[0009] Additional features of the invention will be explained by the detailed following
description with reference to the experimental examples, and by the enclosed figures.
Brief description of the figures
[0010]
Figure 1 shows a longitudinal section of the device.
Figure 2 shows a longitudinal section of the detail of the stagnation chamber.
Figure 3 shows a three-dimensional representation of the device.
Detailed description of the invention
[0011] With reference to figure 1 the electrochemical device 1 of the present invention
is described, comprising:
two electrodes, a first electrode with tubular shape and circular section (cathode)
2 and a second electrode with tubular shape and circular section (anode) 3, arranged
inside the first electrode 2 and coaxial thereto, to form a space between the two
electrodes being divided in two chambers by a membrane wall 4 concentric to the first
electrode, wherein a cathode chamber 5 is arranged between the first electrode 2 and
the membrane wall 4 and an anode chamber 6 is arranged between the second electrode
3 and the membrane wall 4 and
two sealing bushings, an upper bushing 7 and a lower bushing 8 arranged at the ends
of the two electrodes 2 and 3, wherein the lower bushing 8 has an inlet channel of
the electrolytes to the cathode chamber 9 and an inlet channel of the electrolytes
to the anode chamber 10 and the upper bushing 7 has an outlet channel of the electrolytes
from the anode chamber 11 and an outlet channel of the electrolytes from the cathode
chamber 12,
wherein


Db being the internal diameter measurement of the second electrode with tubular shape
and circular section (anode), Db being from 0.1 Ds to 0.7 Ds,
Ds being the internal diameter measurement of the first electrode with a tubular shape
with circular section (cathode)
Dd being the internal diameter measurement of the membrane wall, Dd being from 0.15
Ds to 0.8 Ds;
K being the measurement of the distance between the electrodes;
L being the measurement of the distance between the inlet and outlet channels of the
electrodes;
Ss being the measurement of the area of the cross section of the cathode chamber;
Sb being the measurement of the area of the cross section of the anode chamber;
a stagnation chamber 13 with spheroidal shape opened to the cathode chamber 5 and
positioned at the intersection between the cathode chamber 5 and the outlet channel
of the electrolytes from the cathode chamber 12,
and connected with the outlet channel of the electrolytes from the cathode chamber
12 by a connector pipe 14 wherein


D being the diameter measurement of the outlet collector of the cathode chamber;
r being the measurement of the radius of the stagnation chamber;
d being the diameter measurement of the connector pipe.
[0012] During the electrochemical activation process, which is performed in the device the
present invention relates to, the electrolytes from the inlet channel in the lower
bushing enter the lower portion of the (outer) cathode chamber delimited by the wall
of the electrode with cylindrical shape and by the ion exchange membrane; from this
point they move through the cathode chamber towards the upper bushing wherein they
direct towards the outlet channel of the electrolysis products, crossing the stagnation
area which characterizes the present invention.
[0013] On the contrary, from the inlet channel the electrolytes move through the inner anode
chamber as far as the outlet channel existing in the upper bushing.
[0014] The device is used for the preparation of hypochlorous acid (HOCl) from water and
chloride salts.
[0015] The presence of a stagnation area allows the separation between gaseous and electrolyte
phase and then it avoids the formation on the upper portion of the cathode chamber,
at the upper bushing, of gaseous areas, for example of H
2, which determine a higher consumption of electrical energy.
[0016] In the specific case, the gas, for example H
2, which forms in the stagnation chamber 13 is removed from the cathode chamber 5,
by the connector pipe 14.
[0017] In this way, however, the proposed solution does not determine a simple removal of
the gaseous area which has formed, but it allows even to keep partially dissolved
the gas which has formed in the gaseous area so as to reduce the friction between
the electrolytical solution and the material constituting the device, since the contact
between the solid phase and the gaseous phase determines a lower friction with respect
to the liquid phase-solid phase combination. The reduction in friction between phases
determines a reduction in load losses of the electrolytical solution and therefore
a wear reduction of the device itself.
[0018] Preferably the membrane wall is an ion exchange membrane.
[0019] In an embodiment of the present invention the lower and upper bushings are sealed
by means of seals made of rubber positioned under the ion exchange membrane and the
cylinder-shaped electrode, apart from the sealing ring existing around the bar-shaped
electrode.
[0020] In an embodiment of the present invention the section of the bar-shaped electrode
is uniform to the upper and lower thread of the bushing, which is provided with a
coaxial opening for the bar-shaped electrode, with two cables with cylindrical shape
to place the ion exchange membrane and the cylindrical electrode.
[0021] In an embodiment of the present invention the electrochemical device is characterized
by the following geometrical sizes:
Db = 15.9 mm
Ds = 35.6 mm
Db/Ds=0.4466
Dd = 23.2 mm
Dd/Ds = 0.65168
K = 9.85 mm
L = 260 mm
ln(L) = 5.56
K/ln(L) = 1.68
Ss = 401.4248 mm2
Sb = 224.176 mm2
Ss/Sb = 1.795
r = 3.75 mm
d = 2.1 mm
D = 6 mm
[0022] In the embodiment of the present invention the electrochemical device of the present
invention is used for the preparation of hypochlorous acid (HOCl) from water and sodium
chloride (NaCl).
1. An electrochemical device (1) comprising
two electrodes, a first electrode with tubular shape and circular section (cathode)
(2) and a second electrode with tubular shape and circular section (anode) (3) placed
inside the first electrode (2) and coaxial thereto, to form a space between the two
electrodes being divided in two chambers by a membrane wall (4) concentric to the
first electrode, wherein a cathode chamber (5) is arranged between the first electrode
(2) and the membrane wall (4) and an anode chamber (6) is arranged between the second
electrode (3) and the membrane wall (4) and two sealing bushings, one upper bushing
(7) and one lower bushing (8) arranged at the ends of the two electrodes (2) and (3),
wherein the lower bushing (8) has an inlet channel of the electrolytes to the cathode
chamber (9) and an inlet channel of the electrolytes to the anode chamber (10) and
the upper bushing (7) has an outlet channel of the electrolytes from the anode chamber
(11) and an outlet channel of the electrolytes from the cathode chamber (12), wherein
65 Dd/Ds ≤ K/ln(L) ≤ 25 Db/Ds
0.6 ≤ Ss/Sb ≤ 1.9
Db being the internal diameter measurement of the second electrode with tubular shape
and circular section (anode), Db being from 0.1 Ds to 0.7 Ds, Ds being the internal
diameter measurement of the first electrode with tubular shape and circular section
(cathode), Dd being the internal diameter measurement of the membrane wall, Dd being
from 0.15 Ds to 0.8 Ds, K the measurement of the distance between the electrodes,
L being the measurement of the distance between the inlet and outlet channels of the
electrodes, Ss being the measurement of the area of the cross section of the cathode
chamber, Sb being the measurement of the area of the cross section of the anode chamber;
a stagnation chamber (13) with spheroidal shape opened to the cathode chamber (5)
and positioned at the intersection between the cathode chamber (5) and the outlet
channel of the electrolytes from the cathode chamber (12),
and connected with the outlet channel of the electrolytes from the cathode chamber
(12) by a connector pipe (14) wherein r<D< 3r and d<r< 3d, D being the diameter measurement
of the outlet collector of the cathode chamber, r being the measurement of the radius
of the stagnation chamber, d being the diameter measurement of the connector pipe.
2. The electrochemical device according to claim 1 wherein the membrane wall (4) is an
ion exchange membrane.
3. The electrochemical device according to claim 1 wherein the section of the second
electrode with tubular shape and circular section (anode) is uniform to the upper
and lower thread of the bushing, which is provided with a coaxial opening for the
second electrode with tubular shape and circular section (anode), two cables with
cylindrical shape to place the membrane wall and the first electrode with tubular
shape and circular section (cathode).
4. A use of the device according to anyone of the preceding claims for the preparation
of hypochlorous acid (HOCl) from water and chloride salts.
1. Elektrochemische Vorrichtung (1), aufweisend
zwei Elektroden, eine erste Elektrode mit röhrenförmiger Form und kreisförmigem Querschnitt
(Kathode) (2) und eine zweite Elektrode mit röhrenförmiger Form und kreisförmigem
Querschnitt (Anode) (3), die innerhalb der ersten Elektrode (2) angeordnet ist und
koaxial dazu ist, um einen Raum zwischen den zwei Elektroden zu bilden, der durch
eine Membranwand (4) in zwei Kammern geteilt ist, die konzentrisch zur ersten Elektrode
ist, wobei eine Kathodenkammer (5) zwischen der ersten Elektrode (2) und der Membranwand
(4) angeordnet ist und eine Anodenkammer (6) zwischen der zweiten Elektrode (3) und
der Membranwand (4) angeordnet ist und zwei Dichtbuchsen, eine obere Buchse (7) und
eine untere Buchse (8), die an den Enden der beiden Elektroden (2) und (3) angeordnet
sind, wobei die untere Buchse (8) einen Einlasskanal der Elektrolyte zur Kathodenkammer
(9) und einen Einlasskanal der Elektrolyte zur Anodenkammer (10) aufweist und die
obere Buchse (7) einen Auslasskanal der Elektrolyte von der Anodenkammer (11) und
ein Auslasskanal der Elektrolyte von der Kathodenkammer (12) aufweist, wobei


wobei Db die Innendurchmessermessung der zweiten Elektrode mit röhrenförmiger Form
und kreisförmigem Querschnitt (Anode) ist, Db von 0,1 Ds bis 0,7 Ds ist, Ds die Innendurchmessermessung
der ersten Elektrode mit röhrenförmiger Form und kreisförmigem Querschnitt (Kathode)
ist, Dd die Innendurchmessermessung der Membranwand ist, Dd von 0,15 Ds bis 0,8 Ds
ist, K die Messung des Abstands zwischen den Elektroden ist, L die Messung des Abstands
zwischen den Einlass- und Auslasskanälen der Elektroden ist, Ss die Messung der Fläche
des Querschnitts der Kathodenkammer ist, Sb die Messung der Fläche des Querschnitts
der Anodenkammer ist;
eine Stagnationskammer (13) mit kugelförmiger Form, die zur Kathodenkammer (5) geöffnet
ist und am Schnittpunkt zwischen der Kathodenkammer (5) und dem Auslasskanal der Elektrolyte
von der Kathodenkammer (12) positioniert ist,
und mit dem Auslasskanal der Elektrolyte von der Kathodenkammer (12) durch ein Verbindungsrohr
(14) verbunden ist, wobei r < D < 3r und d < r < 3d ist, wobei D die Durchmessermessung
des Auslasskollektors der Kathodenkammer ist, r die Messung des Radius der Stagnationskammer
ist, d die Durchmessermessung des Verbindungsrohrs ist.
2. Elektrochemische Vorrichtung nach Anspruch 1, wobei die Membranwand (4) eine lonenaustauschmembran
ist.
3. Elektrochemische Vorrichtung nach Anspruch 1, wobei der Querschnitt der zweiten Elektrode
mit röhrenförmiger Form und kreisförmigem Querschnitt (Anode) gleichmäßig zum oberen
und unteren Gewinde der Buchse ist, die mit einer koaxialen Öffnung für die zweite
Elektrode mit röhrenförmiger Form und kreisförmigem Querschnitt (Anode) bereitgestellt
ist, zwei Kabel mit zylindrischer Form zur Platzierung der Membranwand und der ersten
Elektrode mit röhrenförmiger Form und kreisförmigem Querschnitt (Kathode).
4. Verwendung der Vorrichtung nach einem der vorstehenden Ansprüche zur Herstellung von
Hypochlorsäure (HOCL) aus Wasser und Chloridsalzen.
1. Dispositif électrochimique (1) comprenant
deux électrodes, une première électrode de forme tubulaire et de section circulaire
(cathode) (2) et une seconde électrode de forme tubulaire et de section circulaire
(anode) (3) placée à l'intérieur de la première électrode (2) et coaxiale à celle-ci,
pour former un espace entre les deux électrodes divisé en deux chambres par une paroi
de membrane (4) concentrique à la première électrode, dans lequel une chambre de cathode
(5) est agencée entre la première électrode (2) et la paroi de membrane (4) et une
chambre d'anode (6) est agencée entre la seconde électrode (3) et la paroi de membrane
(4) et deux bagues d'étanchéité, une bague supérieure (7) et une bague inférieure
(8) agencées aux extrémités des deux électrodes (2) et (3), dans lequel la bague inférieure
(8) présente un canal d'entrée des électrolytes vers la chambre de cathode (9) et
un canal d'entrée des électrolytes vers la chambre d'anode (10) et la bague supérieure
(7) présente un canal de sortie des électrolytes à partir de la chambre d'anode (11)
et un canal de sortie des électrolytes à partir de la chambre de cathode (12), dans
lequel

Db étant la mesure du diamètre interne de la seconde électrode de forme tubulaire
et de section circulaire (anode), Db allant de 0,1 Ds à 0,7 Ds, Ds étant la mesure
du diamètre interne de la première électrode de forme tubulaire et de section circulaire
(cathode), Dd étant la mesure du diamètre interne de la paroi de membrane, Dd allant
de 0,15 Ds à 0,8 Ds, K la mesure de la distance entre les électrodes, L étant la mesure
de la distance entre les canaux d'entrée et de sortie des électrodes, Ss étant la
mesure de l'aire de la section transversale de la chambre de cathode, Sb étant la
mesure de l'aire de la section transversale de la chambre d'anode ;
une chambre de stagnation (13) de forme sphéroïdale ouverte sur la chambre de cathode
(5) et positionnée à l'intersection entre la chambre de cathode (5) et le canal de
sortie des électrolytes à partir de la chambre de cathode (12),
et raccordée au canal de sortie des électrolytes à partir de la chambre cathodique
(12) par un tuyau de raccordement (14) dans lequel r < D < 3r et d < r < 3d, D étant
la mesure du diamètre du collecteur de sortie de la chambre de cathode, r étant la
mesure du rayon de la chambre de stagnation, d étant la mesure du diamètre du tuyau
de raccordement.
2. Dispositif électrochimique selon la revendication 1, dans lequel la paroi de membrane
(4) est une membrane échangeuse d'ions.
3. Dispositif électrochimique selon la revendication 1, dans lequel la section de la
seconde électrode de forme tubulaire et de section circulaire (anode) est uniforme
par rapport aux filetages supérieur et inférieur de la bague, qui est pourvue d'une
ouverture coaxiale pour la seconde électrode de forme tubulaire et section circulaire
(anode), deux câbles de forme cylindrique pour placer la paroi de membrane et la première
électrode de forme tubulaire et de section circulaire (cathode).
4. Utilisation du dispositif selon l'une quelconque des revendications précédentes pour
la préparation d'acide hypochloreux (HOCl) à partir d'eau et de sels de chlorure.