HK1086861B - Apparatus for carrying out an electrolytic process on a halogenide compound - Google Patents

Description

Device for carrying out an electrolytic process on a halide compound

The invention relates to a device for carrying out an electrolytic process on halide compounds, in which several electrolytic cells (electrolytic cells) are electrically connected in series, each of said cells comprising: a cell element provided with a lower supply pipe for supplying electrolyte and with a collecting discharge pipe arranged close to its upper side for discharging electrolyte and gases formed during the electrolysis process; a cathode chamber including a cathode and an anode chamber including an anode; and a membrane or semi-permeable membrane; wherein the electrolytic cells have been pressed together with a bias between two end plates (end plates) so that each anode chamber and each cathode chamber together with the supply pipe and the collecting discharge pipe are constructed as one unit.

From U.S. Pat. No.5,064,514 there is known an apparatus for preparing chloric acid (chlorous acid) from hypochlorous acid (hypochlorous acid), which apparatus comprises only one single cell configuration. The device known from said document therefore does not comprise a bipolar electrode or an intermediate plate. The cooling system for the device consists of two cooling plates disposed adjacent to the anode and cathode backing plates, the plates having a hollowed out or grooved area that is open on the side adjacent to the cathode and anode, but which is closed and solid at the cooling plate surface on the side adjacent to the backing plate. The grooved zone will permit circulation of a coolant in order to control the heat generated during the electrolysis process. Due to the configuration used herein, the coolant is in direct electrical contact with the electrode.

From us patent No.5,082,543 an electrolytic cell of the filter press type for the production of peroxy (peroxy) and perhalogenate compounds is known. The cells known from said document are of the semi-filter press type, since each cell is separately electrically connected. Therefore, no bipolar electrode or intermediate plate is used. The electrodes used, which are made entirely of metal, are double-walled, between which parallel walls a coolant is pumped. In practice, complete immersion of the bath in the coolant is not possible due to the large number of electrical connections. Due to the construction of the double-walled electrode, the coolant passing therethrough is at the electrode voltage.

A reactor for generating ozone is known from german published specification No 19910639; however, the document does not provide any information about the electrolytic cell used.

The apparatus mentioned in the introduction is known per se from NL 8303210, in which chlorine gas intended for the chlorine treatment of water, such as swimming pool water, drinking water or waste water, is prepared by means of an electrolysis process. The dutch publication shows an electrolytic cell consisting of two anode chambers and two cathode chambers arranged in alternating relationship. Disposed between the first anode compartment and the first cathode compartment is a membrane made of a material suitable for the purpose, which is permeable to cations and impermeable to anions. A similar modular cell unit is formed of a second anode chamber, a second cathode chamber, and a cation permeable membrane disposed therebetween. The modular cell units are positioned adjacent to each other with a liquid impermeable liner or insulator inserted. Rows of end plates are provided at the ends of the cell structure through which tie rods (tie rod) or other suitable fixing means are passed, which also extend through the cells to hold the entire structure together in this manner. Each cell element is provided with a collecting tube, also called degasser (degasser), in which the gases formed during the electrolysis process are separated from the electrolyte.

A disadvantage of the above-described apparatus is the fact that the temperature of the series-connected electrolytic cells can rise to undesirable levels. For chemical and mechanical reasons it is desirable in practice to have the possibility to influence the temperature. In practice, so-called heat exchangers are used for this purpose, which heat exchangers are however installed outside the cell block, which means that the temperature is influenced externally. Such external influences, however, do not prevent the electrolytic cell from exhibiting impermissible thermal deviations, in particular in the center of the cell package. It is therefore desirable to provide a device by means of which the thermal influence can be achieved mainly at the location where the thermal deviation is greatest.

It is therefore an object of the present invention to provide an apparatus for performing an electrolytic process on halide compounds, which apparatus provides the possibility of internal thermal influence at the location where the thermal deviation originates, thereby ensuring internal thermal stability.

It is another object of the present invention to provide an apparatus for performing an electrolytic process on halide compounds that collects corrosive liquids or gases that may have formed as a result of a leak.

According to the invention, the invention as mentioned in the introduction is characterized in that the assembly of end plates and electrolytic cells is present in a container containing liquid, heat transfer medium, wherein a non-conductive cell partition (partition) is present between the cathode and the anode, which cell partition comprises, in addition to a supply pipe and a collecting discharge pipe corresponding to the cell elements, one or more through channels (through channels) for the passage therethrough of the heat transfer medium present in the container, which channels have been formed in the cell partition in such a way that the heat transfer medium present in the channels is not under voltage and that no liquid contact takes place between the electrolyte present in the electrolytic cells and the heat transfer medium present in the container outside the electrolytic cells.

According to the invention, the entire cell package comprising the two end plates is thus placed in a heat transfer medium, such as water, wherein the heat transfer medium actually performs two functions, namely the function of a cooling medium, both internally in the through channels present in the cell partition and externally outside the electrolytic cell in the container, and the function of preventing any leaking medium. Since a significant part of the electrical energy supplied for the electrolysis process as a result of the cooling action achieved in the present invention is collected in the heat transfer medium, energy recovery becomes possible as a result of which energy savings are achieved.

In principle, the through-channels used in the present invention may have any conceivable shape, such as circular, rectangular, trapezoidal, etc. The invention is particularly useful in environments where gaseous halides are desired, for example as disinfectants for swimming pools or drinking water.

In a preferred embodiment, each combination of cathode and anode is separated by a current cell partition, so that the cooling function will always be performed at the location of heat generation. Preferably bipolar electrodes are used.

In a particular embodiment, it is desirable for the heat transfer medium present in the container to pass in a forced manner through a through-passage, which may be achieved, for example, by placing one or more pumps.

The heat transfer medium present in the container can also be utilized for regulating the temperature in the electrolytic cell package and thus the temperature of the electrolytic process, for example by changing the temperature and/or circulation rate of the medium, for example by means of forced circulation, using one or more pumps. Since the entire electrolysis unit is immersed in the heat transfer medium, the risk of gas or electrolyte leaking out is also prevented.

A particular embodiment of the invention is characterized in that a reversing element (reversing element) is provided adjacent to the electrolytic cell package, which reversing element is provided with a lower supply pipe for supplying electrolyte to the adjacent electrolytic cell package and is further provided with a collecting discharge pipe provided near its upper side for discharging electrolyte in the adjacent electrolytic cell package and gases formed during the electrolysis process for effecting a return of electrolyte from the collecting discharge pipe to the supply pipe, which reversing element is provided with one or more through channels for the passage of the heat transfer medium, wherein the channels are configured such that no liquid contact takes place between electrolyte present in the electrolytic cell and the heat transfer medium present in the container outside the electrolytic cell.

In a particular embodiment, said non-conductive cell separation is provided with means for electrically interconnecting the respective adjacent electrodes without any exchange of electrolyte between the two electrolytic cells via said connection or electrolytic corrosion between the respective electrode metals taking place.

In addition to this, it is possible to lead the spent electrolyte to be discharged after the electrolysis process through a heat transfer medium present in the container via a pipe, so that the thermal energy contained in the electrolyte is transferred to the heat transfer medium.

The invention will be described in the following with reference to a number of drawings, which, however, should not be construed as limiting the invention.

Fig. 1 is a perspective view of the present apparatus.

Fig. 2 is a schematic cross-sectional view of the apparatus of fig. 1.

FIG. 3 is a schematic representation of the current pool separation.

FIG. 4 is a schematic representation of the cell separation of FIG. 3.

According to fig. 1, two electrolytic cells of the filter-press type, electrically connected in series, are present in a vessel 1, said vessel 1 containing a heat transfer medium 2, such as water; for the sake of simplicity, the elements for supplying the electrolyte, for example HCl, are not shown in the figures. It should be understood that the present invention is by no means limited to these. The anode 14 is separated from the cathode 15 by a semi-permeable membrane 6. The cathode 15 is separated from the anode 16 by means of the cell partition 9, while the anode 16 is separated from the cathode 17 by the semi-permeable membrane 6. The electrolyte passing through the electrolytic cell via the collecting discharge pipes 13, 19 and the supply pipes 7 and 22 for supplying electrolyte is subjected at the anode to an electrolysis process during which chlorine gas is formed, which for example ends up in the collecting discharge pipe 19 via the anode chamber and subsequently leaves the apparatus via the gas discharge pipe 12. Due to the electrolysis process, hydrogen gas is formed at the cathodes 15, 17, which hydrogen gas originates from the cathode chambers and is collected in the collecting discharge pipe 13, in which collecting discharge pipe 13 separation between electrolyte and hydrogen gas takes place. From the collecting discharge pipe 13, the still hot electrolyte can then be discharged from the apparatus via a pipe 24, which pipe 24 is led through the medium in order to achieve energy transfer. Finally, the hydrogen that has been formed in the electrolysis installation is discharged via the pipe 11. In order to achieve a proper electrolyte flow in the present apparatus, it is preferred to use a reversing element 4, which is provided with a lower supply pipe for supplying electrolyte to the adjacent electrolytic cell package and which is further provided with a collecting discharge pipe arranged near its upper side for discharging electrolyte in the adjacent electrolytic package and gases formed during the electrolytic process for achieving a return of electrolyte from the collecting discharge pipe to the supply pipe. In order to be able to control the temperature of the electrolyte present in the reversing element, the reversing element is provided with one or more through channels (not shown) for the passage of the heat transfer medium 2 therethrough, the channels being configured such that no liquid contact takes place outside the electrolytic cell between the electrolyte present in the electrolytic cell and the heat transfer medium present in the container.

FIG. 2 is a schematic side view of the electrolysis apparatus of FIG. 1. The flow of electrolyte in the cell package is indicated in fig. 2 by means of arrows, from which it is apparent that the reversing element 4 is arranged to return liquid from the collecting discharge pipes 13, 19 to the supply pipes 7 and 22 for supplying electrolyte to the cell in question.

Fig. 3 is a sectional view of an embodiment of the present cell partition 9, in which the through-channels 20 are schematically shown. In particular by passing a heat transfer medium through the channels 20, said passing channels 20 being arranged to allow temperature regulation to take place mainly where heat release takes place, i.e. on the electrode surface. The cell partition 9 shown in fig. 3 may be formed by two symmetrical halves, in one of which (or in each of which) the through channel 20 has been milled out, after which the two halves have been assembled to form one unit comprising the through channel 20. By so arranging the channels at a slight angle, the channels will easily be filled with heat transfer medium once the whole of the end plate and the electrolytic cell is immersed in the heat transfer medium.

Fig. 4 shows the cell separation 9 with the anode 16 arranged on one side and the cathode 15 on the other side. The anode 16 and the cathode 15 are electrically interconnected via connections 21, 23 consisting of two different metals, which connections 21, 23 are designed such that no exchange of electrolyte between the two electrolytic cells can take place via said connections 21, 23. It will be apparent from fig. 4 that, in particular by passing the heat transfer medium 2 through the cell separation 9 via one or more through-channels 20, any cooling that may be required will take place where heat release mainly takes place, i.e. close to the anode 16 and cathode 15.

Claims (5)

1. An apparatus for performing an electrolytic process on a halide compound, in which apparatus several electrolytic cells are electrically connected in series, each of said electrolytic cells comprising: -a cell element (5, 8) provided with a lower supply pipe (7, 22) for supplying electrolyte and with a collecting and discharge pipe (13, 19) arranged near its upper side for discharging electrolyte and gases formed during the electrolytic process; a cathode compartment comprising a cathode (15, 17) and an anode compartment comprising an anode (14, 16); and a membrane or semi-permeable membrane (6); wherein the electrolytic cell has been pressed together with an offset between two end plates (3, 10) such that each anode compartment and each cathode compartment is constructed as one unit together with the supply pipe and the collecting discharge pipe, characterized in that:

the assembly of end plates and electrolytic cells is present in a container (1) containing liquid, heat transfer medium (2), wherein a non-conductive cell partition (9) is present between the cathodes and anodes of two adjacent electrolytic cells, said cell partition comprising, in addition to supply and collection discharge pipes corresponding to said cell elements, one or more through channels (20) for the passage therethrough of the heat transfer medium present in said container, said channels having been formed in said cell partition such that the heat transfer medium present in said channels is not under voltage and no liquid contact between the electrolyte present in said electrolytic cells and the heat transfer medium present in said container takes place outside said electrolytic cells.

2. An apparatus according to claim 1, characterized in that a reversing element (4) is arranged adjacent to the electrolytic cell package, which reversing element is provided with a lower supply pipe for supplying electrolyte to the adjacent electrolytic cell package and is further provided with a collecting discharge pipe arranged near its upper side for discharging electrolyte in the adjacent electrolytic cell package and gases formed during the electrolysis process in order to achieve a return of electrolyte from the collecting discharge pipe to the supply pipe, which reversing element is provided with one or more through channels for the passage of the heat transfer medium therethrough, which channels are designed such that no liquid contact takes place outside the electrolytic cell between electrolyte present in the electrolytic cell and the heat transfer medium present in the container.

3. An apparatus according to claim 1 or 2, characterized in that said non-conductive cell partition is provided with means for electrically interconnecting the respective adjacent electrodes without any exchange of electrolyte between the two electrolytic cells via said connection or electrolytic corrosion between the respective electrode metals.

4. The apparatus according to claim 1 or 2, characterized in that the electrolyte is discharged from the apparatus via a pipe (24) provided in a heat transfer medium in the container, in order to transfer thermal energy contained in the electrolyte to the heat transfer medium.

5. An apparatus according to claim 3, characterized in that a pipe (24) for discharging electrolyte from the apparatus is arranged in the heat transfer medium in the container for transferring thermal energy contained in the electrolyte to the heat transfer medium.