EA004521B1 - Method and apparatus for the on-site generation of a gas - Google Patents

Abstract

1. A method for the on-site generation of a gas comprising the steps of: a) forming a dissociatable electrolyte solution which, in use, dissociates into positively charged and negatively charged ions at least one of which is an ion of a gaseous element; b) heating the electrolyte solution upstream of at least one electrolytic cell and thereby causing it to circulate and re-circulate through conduits and through the or each electrolytic cell by means of a thermosyphon effect; 2. A method for the on-site generation of a gas as claimed in claim 1 in which circulation of the electrolyte solution is facilitated by entraining gas bubbles produced in the or each electrolysis cell in dissolving tubes mounted substantially horizontally leading from the or each electrolysis cell to the or each gas separator substantially vertically thereby providing a gas lift effect. 3. A method for the on-site generation of a gas as claimed in claim 1 in which the electrolyte concentration in the solution is strengthened, if necessary, and any make up water is saturated by passing the electrolyte and make up water through an electrolyte salt dissolving tube . 4. A method for the on-site generation of a gas as claimed in claim 1in which the electrolyte solution is a metal halide and gas generated at the anolyte side of the electrolysis cell is a halogen. 5. A method for the on-site generation of a gas as claimed in claim 4 in which the metal halide salt is sodium chloride and the and gas generated at the anolyte side of the electrolysis cell is chlorine. 6. A method for the on-site generation of a gas as claimed in claim 5 in which hydrogen gas and sodium hydroxide or potassium hydroxide to be generated at the catholyte side of the electrolysis cell. 7. A method for the on-site generation of a gas as claimed in claim 6 to 13 in which sodium hypochlorite or potassium hypochlorite is also produced by mixing chlorine and sodium hydroxide, or chlorine and potassium hydroxide. 8. An apparatus for the on-site generation of a gas comprising at least one electrolytic cell having an anolyte section and a catholyte section, at least one section being connected, by fluid conduits, to a fluid heater which, in use, heats an electrolyte solution prior to its ingress into said section and facilitates circulation of the electrolyte solution through the apparatus by means of a thermosyphon effect, the electrolytic solution being dissociatable into positively charged and negatively charged ions at least one of which is an ion of a gaseous element, the heating element in turn being connectable by fluid conduits to an electrolyte replenishment means, at least one gas separator which, in use, separates gas produced in the electrolytic cell from electrolyte solution, the apparatus lacking a reservoir for the storage of electrolyte solution. 9. An apparatus for the on-site generation of a gas as claimed in claim 8 in which the or each gas separator is positioned operatively above the or each electrolysis cell and in which conduits linking the or each electrolysis cell is orientated operatively substantially vertically thereby facilitating circulation of the electrolytic solution by means of a gas lift effect. 10. An apparatus for the on-site generation of a gas as claimed in claim 9 in which the replenishment means is a substantially horizontally orientated electrolyte salt dissolving tube through which electrolyte solution from the or each gas separator flows prior to flowing through the heating element. 11. An apparatus for the on-site generation of a gas as claimed in claim 8 in which the salt dissolving tube is connected to an electrolyte salt replenishment hopper which contains a desired salt, and is also connected to a salt separator, which is connected to the heating element, the salt separator removing micro particulate salt from the electrolyte prior to its introduction into the heating element. 12. An apparatus for the on-site generation of a gas as claimed in claim 11 in which the electrolyte is a metal halide solution, the gas generated at the anolyte side of the electrolysis cell to be a halogen and hydrogen gas and a metal halide hydroxide are generated at the catholyte side of the electrolysis cell. 13. An apparatus for the on-site generation of a gas as claimed in claim 12 in which the metal halide is sodium chloride, the gas generated at the anolyte side of the electrolysis cell is chlorine and hydrogen gas and sodium hydroxide are generated at the catholyte side of the electrolysis cell. 14. An apparatus for the on-site generation of a gas as claimed in claim 8 in which the anolyte and catholyte sections of the or each electrolytic cell are separated from one another by an ion selective membrane made of perfluoropolymer which allows the passage of sodium or potassium ions therethrough but which is impermeable to halogen, hydrogen gas and hydroxyl.

Description

This invention relates to a method and apparatus for producing gas at a place of consumption, in particular, but not exclusively, chlorine-containing gas.

BACKGROUND OF THE INVENTION

The presence of a device for producing chlorine-containing gas at the place of consumption has numerous advantages. Chlorine-containing gas is considered a hazardous substance, and its storage and transportation are subject to strict control. In addition to this, and also because of its dangerous status, transportation of tanks with liquid chlorine is expensive. This increases the costs of production plants using this gas.

There is also a market for generators for producing relatively small amounts of chlorine-containing gas at a place of consumption for plants that consume small amounts of chlorine-containing gas. These plants include water and wastewater treatment plants, as well as cooling towers, where the water used in these towers is chlorinated. In order to avoid the need for chlorine storage, these plants could use devices that produce the required amount of chlorine in place. Chlorine-containing gas and sodium hypochlorite are also used as a disinfectant.

In addition, relatively small chlorine-containing gas generators can be used in rural areas to purify water and turn into drinking water that is obtained from small dams and rivers.

In addition to devices for the production of chlorine, there is also a market for devices that produce other gases on demand and at the place of consumption. Such gases may include bromine, used as a means of sterilizing agricultural land and which is particularly effective in combating land nematoses.

Devices producing chlorine gas through electrolysis are well known. These devices produce chlorine-containing gas through the anode of an electrolytic cell through which sodium chloride is passed. Hydrogen-containing gas and sodium hydroxide are formed at the cathode.

Many of the above devices are applicable and used to produce chlorine-containing gas at the place of consumption. One example is disclosed in US Pat. No. 4,308,123. In this example, an electrolytic cell is used that has an anode and a cathode, separated by a chemically resistant ion exchange membrane, passing only positively charged ions. The anode chamber is filled with sodium chloride solution, and the cathode chamber is filled with an alkaline aqueous solution. When an electric current is passed through the chamber, chlorine-containing gas at the anode and hydrogen and sodium hydroxide at the cathode are obtained. The resulting chlorine and sodium hydroxide can be combined to form sodium hypochlorite. The aforementioned device has the disadvantage that feed tanks or reservoirs of anolytes and catholytes are necessary, as well as foam traps of anolytes and catholytes. These containers are a potential hazard, especially in a semi-industrial environment where safety controls may not be carefully monitored.

Moreover, many well-known gas generators need pumps for circulating electrolytic solutions. These pumps require an energy source and often very sophisticated control systems. In addition, they also require regular maintenance, which is a disadvantage in remote areas, especially considering the potentially dangerous nature of the gases produced.

The purpose of the invention

The aim of the present invention is to provide a method and device for producing gases at the place of consumption, in particular chlorine-containing gas, which at least partially eliminate the above disadvantages.

SUMMARY OF THE INVENTION

In accordance with the present invention, a method for producing on-site gas consumption is provided, comprising the following steps:

A) the formation of a dissociable electrolyte solution, which during operation dissociates into positively charged and negatively charged ions, at least one of which is a gaseous cell ion;

B) heating the electrolyte solution in the upper layer of at least one electrolytic cell, which will cause its circulation and recirculation through pipelines and through at least one electrolytic cell by means of the thermosiphon effect;

B) the release of gas from the solution on the electrode of at least one electrolytic cell;

D) passing the released gas and the electrolytic solution through at least one gas separator to separate the gas from the electrolytic solution to recirculate the electrolytic solution in the electrolytic cell; and

D) the exclusion of the electrolyte in the reservoir during the entire process.

Further, for the purpose of circulating the electrolytic solution, the removal of gas bubbles produced in one electrolytic cell or in all electrolytic cells and the orientation of pipelines leading from one electrolytic cell or from all electrolytic cells to a gas separator or to all gas separators, preferably vertically, are provided, thereby ensuring gas lift effect.

The invention also provides for increasing the concentration of the solution, if necessary, and saturation with water to make up for losses by passing it through the pipe to dissolve the electrolytic salt, the pipe being mounted preferably horizontally, as well as replenishing the electrolytic salt in the pipe with fresh salt, preferably from the hopper.

The invention provides that the electrolytic solution is a metal halide, preferably sodium chloride, alternatively potassium chloride.

It is further provided that the anode and cathode sections of the electrolytic cell or all electrolytic cells must be separated from each other by an ion selective membrane, preferably a perfluorinated polymer membrane, which allows sodium ions, alternatively potassium, to pass through it, but which, however, is impenetrable for ions halogen, preferably chlorine, hydrogen-containing gas and hydroxyl.

It is further contemplated to add water, preferably distilled, alternatively demineralized water, to a solution of sodium hydroxide, alternatively potassium hydroxide, on the cathode side of the electrolytic cell to maintain a predetermined concentration of sodium, alternatively potassium, in the cathode solution.

The following also provides a method for producing sodium hypochlorite, alternatively potassium hypochlorite, by mixing chlorine and sodium hydroxide, alternatively chlorine and potassium hydroxide, obtained by the method according to this invention.

The invention also relates to a device for producing gas at a place of consumption, which includes at least one electrolytic cell having an anode section and a cathode section, wherein at least one section is connected by liquid pipes to a liquid heater that heats the electrolytic solution before operation getting into the indicated section, and provides the circulation of the electrolytic solution through the device using the thermosiphon effect, while the electrolytic solution is capable of dissociation and positively charged and negatively charged ions, at least one of which is an ion of a gaseous element. The heating element, in turn, can be connected by means of pipelines for liquid with a device for compensating the solution. At least one gas separator is provided, which during operation separates the gas obtained in the electrolytic cell from the electrolytic solution, while there is no reservoir for storing the electrolytic solution.

Further, it is envisaged that each gas separator should be quickly installed above the electrolytic cell or over all electrolytic cells, and the pipelines connecting them should be oriented vertically, thereby allowing the circulation of the electrolytic solution through the gas lift effect.

A replenishment device is also provided, which is preferably a horizontally oriented pipe for dissolving the electrolyte salt, through which the electrolytic solution flows from the gas separator or from all gas separators before flowing through the heating element, while the pipe for dissolving the salt must be connected to the loading hopper for replenishing the electrolytic salt containing the desired salt, and also that the pipe for dissolving the salt should be connected to a salt separator, preferably with a filter ohms, is connected with the heating element and which during operation removes particulate salt from the electrolyte prior to its introduction into the heating element.

The invention further provides that the electrolyte should be a solution of a metal halide, preferably sodium chloride, alternatively potassium chloride, that the gas obtained on the anode side of the electrolytic cell should be halogen, preferably chlorine, and that a hydrogen-containing gas and sodium hydroxide, alternatively potassium, should be obtained on the cathode side of the electrolytic cell.

It is further provided that the anode and cathode sections of the electrolytic cell or all electrolytic cells must be separated by a perfluorinated polymer membrane that allows sodium ions, alternatively potassium, to pass through it, but which is impassable for chlorine-containing and hydrogen-containing gas.

It is further contemplated to add water, preferably distilled, alternatively demineralized, to a solution of sodium hydroxide, alternatively potassium, on the cathode side of the electrolytic cell to maintain the concentration of sodium hydroxide, alternatively potassium, in the cathode solution.

A device is also provided for producing sodium hypochlorite, alternatively potassium hypochlorite, by mixing chlorine and sodium hydroxide, alternatively potassium hydroxide, prepared in accordance with this invention.

Brief Description of the Drawings

One embodiment of the invention is described below by way of example only and with reference to the accompanying drawings, in which FIG. 1 is a schematic diagram of an embodiment of a method for producing on-site chlorine-containing gas in accordance with this invention;

FIG. 2A-C are, respectively, a schematic first side view, a schematic second side view, and a schematic top view of a device for receiving in place chlorine-containing gas in accordance with the method of FIG. 1 and FIG. 3A-C are respectively a front view, a top view and a side view in section of a matrix of electrolysis cells used in the device shown in FIG. 2.

Detailed description with reference to the drawings

With reference to FIG. 1 method of producing chlorine-containing gas at the place of consumption includes the steps of:

A) the formation of the first, capable of dissociation of an electrolytic solution of sodium chloride or saline solution (1), which is transported through a pipe (2) to the anode section (3) of the electrolytic cell (7), and the second, capable of dissociation of an alkaline aqueous solution (4) which is transported through a pipeline (5) to the cathode section (6) of the electrolytic cell (7), which is divided into sections by a membrane of perfluorinated polymer (8), which allows sodium ions to pass through it and is impenetrable for chlorine, hydrogen and hydrogen ions oxide;

B) heating the first electrolytic solution capable of dissociating solution (1) before transporting it to the anode section (3) of the electrolytic cell (7), which thereby causes its circulation and recirculation through pipelines and through the electrolytic cell (7) by means of a thermosiphon effect;

B) the release from electrolytic solutions of chlorine-containing gas from the anode section (3) and hydrogen-containing gas from the cathode section (6);

D) the removal of bubbles of chlorine-containing and hydrogen-containing gases in electrolytic solutions, which ensures the circulation of electrolytic solutions through gas lift and the collection of chlorine-containing gas (9) and hydrogen-containing gas (10);

D) this method is characterized in that during the entire process the electrolytic solution is not stored in the tank.

In the above embodiment, the electrolytic cell (7) has an anode in its anode section (3) and a cathode in its cathode section (6). The anode and cathode are connected to the positive and negative poles of the direct current source (11), which in this embodiment is a direct current converter. The DC / DC converter (11) receives alternating current from a suitable alternating current source (12).

When the salt in the first dissociable electrolytic solution (1) is depleted, it is restored by adding salt from the feed salt hopper (14) to a preferably horizontally oriented tube for dissociating the electrolytic salt, through which the first chlorinated electrolytic solution circulates before filtering, heating and by recirculation to the electrolytic cell (7).

As the solution on the anode side is depleted in volume, it is compensated by adding pure fresh brine (200) to the system. This pure fresh brine is obtained in the interior 201, where tap water is passed through a separate salt dissolution pipe similar to that described in (1) above, including a separate salt separator / filter, and the saturated solution thus formed is then passed through a column containing the appropriate the type of polymer by which anionic contaminants of heavy metals are removed before the purified solution is sent through pipeline (200) to the anode system (1). The second, electrolytic solution capable of dissociation (4) is restored by adding water from a water source (13) after it has passed through a demineralizing unit (15). In addition to chlorine-containing and hydrogen-containing gas, this method involves the production of sodium hypochlorite in a reactor (16). Sodium hypochlorite is formed by combining chlorine and sodium hydroxide obtained in the anolyte and catholytic sections (3 and 6) of the electrolytic cell (7), respectively. The obtained sodium hypochloride is stored in the device (17).

Sodium hydroxide obtained in the cathode section (6) of the electrolytic cell (7) can also be separated and stored in a container (18).

With reference to FIG. 2A, B and C, a device (20) for producing a chlorine-containing gas includes at least one electrolytic cell (21) having an anode and cathode sections. At least one section, which in this embodiment is the anode section, is connected by a pipe (22) to a liquid heater (23), heating the electrolytic solution during operation until it enters the indicated section of the electrolytic cell (21), and circulates the electrolytic solution through the device through the effect of thermosiphon.

The electrolytic solution is capable of dissociation into positively and negatively charged ions, at least one of which is a gaseous cell ion. In this embodiment, a chlorine-containing gas and an electrolytic solution in the anode are obtained.

Ί section of the device, which turns into a solution of acid sodium chloride, when chlorine is met with water to produce hypochlorous acid, which dissociates into positively charged sodium and hydrogen ions and negatively charged chlorine and hydroxyl ions. Chlorine and hydrogen ions combine with similar ions to form a chlorine-containing and hydrogen-containing gas, each of which circulates together with the electrolyte solution through gas separators (24 and 25), which separate the chlorine-containing gas and hydrogen-containing gas from the electrolytic solutions, respectively. In this embodiment, the hydrogen-containing gas is waste, and it is vented to the atmosphere, while the chlorine-containing gas is used or further processed to produce sodium hypochloride by combining chlorine with sodium hydroxide, both of which are produced by this device.

Each electrolytic cell (21) is separated into the anode section and the cathode section using a perfluorinated polymer membrane, which allows sodium ions to pass through it, but does not allow ions of chlorine, hydrogen, or hydroxyl to pass through it. This membrane effectively separates the device as well as the electrolytic cell into the anode section and the cathode section.

As the electrolyte passes through the anode section of the electrolytic cell (21), a chlorine-containing gas is formed on the anode, and it is carried away into the electrolytic solution, which is depleted. Captured gas bubbles circulate the electrolyte and trapped gas bubbles to the chlorine-containing gas separator (24) by gas lift. After passing through the chlorine-containing gas separator (24), the depleted electrolyte flows through the pipe (26) and enters a horizontally oriented pipe to dissolve the electrolyte salt (27), which is supplied with the sodium chloride salt from the salt hopper (28) through the chute (29). In the pipe (27) for dissolving the salt, the electrolyte solution is restored. Salt crystals in the electrolyte solution are removed by passing the recovered electrolyte solution through a salt separator and filter (30), from where it returns to the liquid heater (23) to repeat the process.

When the electrolyte passes through the cathode section of the electrolytic cell (21), hydrogen gas is released at the cathode. Bubbles of hydrogen gas, as well as chlorine-containing gas, are carried away into the electrolytic solution and ensure its circulation through the hydrogen gas separator (25). After the removal of hydrogen and sodium hydroxide, water is added that passes through the demineralizing column (31) in order to restore the cathode electrolyte solution, which flows through the cathode section of the electrolytic cell (21).

The cathodic electrolytic solution does not directly heat up, as occurs in the anodic electrolytic solution. However, it is heated in the electrolytic cell (21) as a result of the fact that it is in contact with a heated solution of the anode electrolyte. It is contemplated that heating the anode electrolyte solution before it is placed in the electrolytic cell increases the efficiency of the gas production process since the electrolyte has its optimum temperature. The electric current for the anode, cathode and heater comes from the AC network. When current is connected to the anode and cathode, it passes through a DC / DC converter (not shown).

With reference to FIG. 3A, B and C show details of a series of electrolytic cells (40) for use in the device of FIG. 2. In the present embodiment, there are two electrolytic cells (40), each separated by a membrane of perfluorinated polymer (41), which transmits sodium ions, but does not pass ions of chlorine, hydrogen and hydroxyl.

Each cell (40) has an anode (42), on which a chlorine-containing gas is obtained, and a cathode (43), on which a hydrogen-containing gas is obtained. Cells (40) are formed by bolting together a series of plates (plates), two of which are end plates (44), which have inputs (45) and conclusions (46) for the anode electrolyte solution and inputs (47) and conclusions (48) ) for a solution of cathode electrolyte. Internal spacer plates (100) form oppositely charged barriers through which the anode electrolyte solution flows, starting from the bottom corner of the plate and sequentially through the cell and flowing out from the opposite upper corner. Similarly, the cathode electrolytic solution enters the cell from the opposite lower angle with respect to the anode electrolytic solution and exits at the opposite upper side. Anolyte and catholyte thus flow countercurrently, which during operation maximizes efficiency. The installation is bolted using the support plates (101) and bolts (102).

It is obvious that can be implemented numerous options for the above technical solution, without deviating from its essence. These options, in particular, provide a method and apparatus for producing a chlorine-containing gas and a hydrogen-containing gas. The same device can be used to produce a chromium-containing gas or in fact any gas that can be obtained by an electrolytic reaction.

Claims (14)

CLAIM 1. A method of producing gas, comprising the following steps: A) formation of an electrolyte solution capable of dissociation, which during operation dissociates into positively charged and negatively charged ions, at least one of which is a gaseous element ion; B) heating the electrolyte solution in the upper layer of at least one electrolytic cell, causing its circulation and recirculation through pipelines and through the electrolytic cell or through each of the electrolytic cells due to the effect of thermosyphon; B) passing the released gas and the electrolytic solution through at least one gas separator to separate the gas from the electrolytic solution before recirculating the electrolytic solution in the electrolytic cell. 2. The method of producing gas according to claim 1, in which the circulation of the electrolytic solution is carried out due to the release of gas bubbles obtained in the electrolytic cell or all electrolytic cells in vertically arranged pipelines leading from the electrolytic cell or each of the electrolytic cells to the gas separator or each gas separators. 3. The method of producing gas according to claim 1, in which the concentration of the electrolyte in the solution, if necessary, increases to compensate for the losses by mixing water with the electrolyte when passing through a horizontally mounted pipe to dissolve the electrolyte salt. 4. The method of producing gas according to claim 1, wherein the electrolytic solution is a metal halide and the gas produced on the anode side of the electrolytic cell is halogen. 5. The method of producing gas according to claim 4, wherein the metal halide salt is sodium chloride or potassium chloride and the gas produced on the anode side of the electrolytic cell is chlorine. 6. The method of producing gas according to claim 5, in which hydrogen gas and sodium hydroxide or potassium hydroxide are obtained on the cathode side of the electrolytic cell. 7. The method of producing gas according to claim 6, in which sodium hypochlorite or potassium hypochlorite is also obtained by mixing chlorine and sodium hydroxide or chlorine and potassium hydroxide. 8. A device for producing gas comprising at least one electrolytic cell having an anode section and a cathode section, wherein at least one section is connected by fluid lines to a liquid heater, which, during operation, heats the electrolytic solution before it enters the specified section and provides electrolytic solution is circulated through the device through a thermosyphon effect, while the electrolytic solution is capable of dissociating into positively charged and negatively ulcerated ions, and at least one of which is an ion of the gaseous element, while the heating element can be connected via liquid pipelines to an electrolyte replenishment device, and at least one gas separator, which during operation separates the gas obtained in the electrolytic cell from the electrolyte solution, and while in the device there is no reservoir for storing the electrolytic solution. 9. A device for producing gas according to claim 8, in which the gas separator or each of the gas separators is installed above the electrolytic cell or over all electrolytic cells and in which the pipelines connected to the electrolytic cell or all electrolytic cells are vertically oriented, which ensures the circulation of the electrolytic solution gas lift effect account. 10. An apparatus for producing gas according to claim 9, wherein the replenishing device is a horizontally oriented pipe for dissolving an electrolytic salt, through which the electrolytic solution flows from the gas separator or from each of the gas separators before flowing through the heating element and which has a filter that removes during operation particulate salt from the electrolyte before it is introduced into the heating element. 11. Apparatus for producing gas according to claim 8, in which the pipe for dissolving the salt is connected to the electrolytic salt feed hopper containing the desired salt and to the salt separator, which is connected to the heating element, while the salt separator removes particulate matter from the electrolyte before introducing it a heating element. 12. An apparatus for producing gas according to claim 11, wherein the electrolyte is a metal halide solution, the gas produced on the anode side of the electrolytic cell is halogen, and hydrogen gas and metal hydroxide are produced on the cathode side of the electrolytic cell. 13. The gas generating apparatus according to claim 12, wherein the metal halide is sodium chloride or potassium chloride, the gas produced on the anode side of the electrolytic cell is chlorine, and hydrogen gas and sodium hydroxide or potassium hydroxide are produced on the cathode side of the electrolytic cell. 14. An apparatus for producing gas according to claim 8, wherein the anodic and cathodic sections of the electrolytic cell or all electrolytic cells are separated from each other by a selective perfluorinated polymer membrane that allows the passage of sodium or potassium ions through it, but impassable for halogen, hydrogen-containing gas and hydroxyl.