JP2023013534A - Tritium-containing water treatment method, treatment business method and treatment apparatus - Google Patents

Abstract

To provide a solution to a problem that many proposed methods for treating tritium-containing water containing tritium that have focused on removing and detoxifying tritium require a large amount of energy for the treatment to be economically disadvantageous.SOLUTION: A business method to be proposed is economically advantageous in that tritium-containing water is electrolyzed using power generated from natural energy, and hydrogen and oxygen gases generated are used to generate power in a fuel cell to detoxify the tritium-containing water, and then the product, tritium, and electrical power are sold.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to treatment of tritium-containing water, and more particularly to a tritium-containing water treatment business, a tritium-containing water treatment method, and a tritium-containing water treatment apparatus.

As a method for treating water containing tritium discharged from a nuclear power plant, for example, a method of diluting tritium-containing water and releasing it into the ocean, or a method of evaporating tritium-containing water to produce high-temperature steam, A method of releasing to the atmosphere has been proposed.

According to Patent Document 1, a first concentration module that concentrates tritium-contaminated water at a low concentration to generate first tritium-enriched water and first tritium-removed water, and first tritium concentration concentrated in the first concentration module A technique has been proposed with a second concentration module that re-concentrates water to a high concentration to produce a second tritiated water and a second tritiated water.

According to Patent Document 2, tritium-contaminated water is heated to generate steam, and the steam is cooled and condensed to obtain condensate. The permeated liquid is diluted with seawater and discharged to the outside. A technique has been proposed in which the vapor generated by heating the concentrated liquid is released into the atmosphere.

Furthermore, according to Patent Document 3, there is a technique comprising a tritiated water separation step of heating contaminated water to generate contaminated steam and centrifuging the contaminated steam to separate tritium-contaminated water from the contaminated steam. Proposed.

JP 2015-188810 A JP 2017-20964 A JP 2015-80748 A

The conventional technology described in Patent Document 1 mentioned above requires a large-scale facility for diluting tritium-containing water (hereinafter referred to as tritium-containing water), and is therefore uneconomical and unsuitable for commercialization.

The conventional techniques described in Patent Documents 2 and 3 have the problem that tritium-containing water needs to be steamed, and a large amount of energy is required to evaporate the tritium-containing water due to the latent heat of water.

In addition, the prior art treats water containing tritium as contaminated water, and focuses on removing tritium to render it harmless while ensuring economic efficiency including energy consumption.

The present invention has been made to solve the above-mentioned problems in the prior art, and is an economically superior method that does not require large-scale equipment and does not use a large amount of energy for treating tritium-containing water. A treatment system for tritium-containing water and a method for its commercialization are proposed.

In order to achieve the above-described object, the tritium-containing water treatment business according to the present invention receives wastewater containing tritium for a fee, uses electricity obtained from natural energy to electrolyze the wastewater, and Separating tritium gas and hydrogen gas from gas containing hydrogen obtained by water electrolysis and selling the tritium gas

According to this configuration, it is possible to effectively utilize power generation using natural energy, which often causes disturbances to the system, without requiring large-scale equipment. In addition, water containing tritium can be treated with reduced energy consumption. Moreover, by using electrolysis, the volume of water containing tritium can be reduced.

In the tritium-containing water treatment business according to the present invention, tritiated water is produced and sold by reacting the oxygen gas obtained by the water electrolysis with the tritium gas.

The tritium-containing water treatment business according to the present invention supplies the hydrogen gas to the fuel cell and sells the electric power from the fuel cell.

In the tritium-containing water treatment business according to the present invention, the water electrolysis is performed in a cascade. In the tritium-containing water treatment business according to the present invention, the tritium gas and hydrogen gas are separated in multiple stages.

The tritium-containing water treatment business according to the present invention treats the water generated by the power generation of the fuel cell as water supply or waste water. In the tritium-containing water treatment business according to the present invention, the tritium gas is compressed and sold.

In the tritium-containing water treatment business according to the present invention, the fuel cell is a fuel cell storage battery. In this configuration, the fuel cell storage battery is a fuel cell with a power storage function. Further, in the tritium-containing water treatment business according to the present invention, electric power from the fuel cell or the secondary battery connected to the fuel cell storage battery is sold. In this configuration, electric power generated by discharging the storage battery and the secondary battery has excellent responsiveness.

In the tritium-containing water treatment business according to the present invention, the secondary battery has donut-shaped electrodes stacked, the outer edge of one of the electrodes is electrically connected to the outer package, and the periphery of the hole of the other electrode is gathered. electrically connected to an electrical body.

In the method for treating tritium-containing water according to the present invention, wastewater containing tritium is received for a fee, the wastewater is subjected to water electrolysis using electricity obtained from natural energy, and the hydrogen obtained by the water electrolysis is contained. tritiated water is produced by separating tritium gas and hydrogen gas from the gas, and reacting the oxygen gas obtained by the water electrolysis with the tritium gas, and supplying the hydrogen gas and the oxygen gas to the fuel cell. Electric power is generated from the fuel cell.

A tritium-containing water treatment apparatus according to the present invention includes a water electrolysis apparatus that electrolyzes water containing tritium, and a separation apparatus that separates tritium gas and hydrogen gas generated from a cathode of the water electrolysis apparatus, A fuel cell is provided for generating power using the hydrogen gas separated by the separator and the oxygen gas generated from the anode of the water electrolysis device. Further, in the apparatus for treating tritium-containing water according to the present invention, a plurality of the water electrolysis apparatuses are cascade-connected, and the separation apparatus according to claim 12 is configured in multiple stages.

Tritium can be separated from tritium-containing water and released in the form of fresh water. In addition, tritium can be extracted from tritium-containing water and sold. Furthermore, electricity can be generated from the tritium-containing water treatment business. The use of renewable energy can be promoted in the process of treating tritium-containing water.

1 is a block diagram for conceptually explaining an outline of a tritium-containing water treatment apparatus; FIG. FIG. 4 is a block diagram illustrating the flow of tritium-containing water when water electrolysis devices are multiplexed; FIG. 4 is a block diagram illustrating the flow of tritium-containing water when separating devices are multiplexed; 1 is an axial cross-sectional view of a laminated secondary battery; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments according to the present invention will be described below with reference to the drawings, but the present invention is not limited to these embodiments.

The inventor considered commercializing removal of tritium from water containing tritium discharged from a nuclear power plant (hereinafter referred to as tritium-containing water). In other words, the idea was to detoxify the tritium-containing water and sell the removed tritium. Before explaining the tritium-containing water treatment business and the treatment method, a tritium-containing water treatment apparatus for realizing them will be explained.

The configuration of the tritium-containing water treatment apparatus will be described using the block shown in FIG. The tritium-containing water treatment device 20 has a water electrolysis device 21, a separation device 24 and a fuel cell 25 as main components.

The water electrolyzer 21 is supplied with tritium-containing water from a tritium-containing water storage tank 31 . An external power supply 30 is connected to the water electrolysis device 21 to supply necessary DC power to the water electrolysis device 21 . The external power source 30 includes, for example, a solar power generation facility 30-1 and a wind power generation facility 30-2. The external power source 30 may be power from a power generator using natural energy, and may be biomass power generation. A small amount of electrolyte is added to the tritiated water to aid electrolysis.

The water electrolysis device 21 includes an electrolytic cell containing tritium-containing water, an anode connected to the positive electrode of the external power source 30, and a cathode connected to the negative electrode of the external power source 30 (all not shown). . When a voltage is applied between the electrodes while the tritium-containing water is in contact with the cathode and anode, hydrogen gas is generated from the cathode due to a reduction reaction at the cathode. During the reduction reaction, tritium contained in the tritium-containing water is also reduced, and tritium gas is generated together with hydrogen gas from the cathode.

A mixed gas of hydrogen gas and tritium gas is sent from the water electrolysis device 21 to the hydrogen tank 22 . The mixed gas of hydrogen gas and tritium gas in the hydrogen tank 22 is separated into hydrogen gas and tritium gas by the separator 24 . Separation methods include, but are not limited to cryogenic separation, pressure swing and centrifugation. For example, when a mixed gas of hydrogen and tritium is cooled with liquefied helium, tritium, which has a high condensation point, liquefies first, and is separated from hydrogen gas. This method is called a cryogenic separation method.

The molecular weight of tritiated water (THO) is 19, while the molecular weight of water is 18. The difference between them is small, making separation of the two difficult. On the other hand, while tritium has a molecular weight of 4, hydrogen has a molecular weight of 2, and their specific gravities are two and a half. In addition to specific gravity, tritium and hydrogen also differ greatly in diffusion rate, freezing point, and boiling point. Therefore, it is easier and more economical to separate tritium by gasifying the tritium-containing water by electrolyzing it than by separating tritium from the tritium-containing water.

Tritium gas (HT) separated by the separator 24 is sent to a tritium tank 26 . The tritium stored in the tritium tank 26 is compressed to an appropriate pressure, packed in cylinders and shipped. The hydrogen gas (H ₂ ) separated by the separator 24 is temporarily supplied to the fuel cell 25 as fuel gas via the hydrogen chamber 27 .

Oxygen gas generated from the anode of the water electrolysis device 21 is sent to the fuel cell 25 via the oxygen tank 23 . The hydrogen gas from the hydrogen chamber 27 and the oxygen gas from the oxygen tank 23 are used by the fuel cell 25 to generate power and supply power to the outside. At this time, high-purity water is produced as a by-product by the oxidation-reduction reaction of hydrogen and oxygen.

The fuel cell 25 functions as a power generator that converts chemical energy directly into electrical energy. Hydrogen gas is electrochemically oxidized at the anode and decomposed into hydrogen ions and electrons. On the other hand, oxygen gas is reduced at the cathode by hydrogen ions and electrons that have passed through the electrolyte to produce water. Since the reaction of the fuel cell 25 proceeds by electrochemical combustion, unlike chemical combustion, the reaction does not reach a high temperature, and the energy conversion efficiency is high. A well-known fuel cell can be used.

The tritium gas in the tritium tank 26 is oxidized and burned in the combustion chamber 28 by the oxygen gas from the oxygen tank 23 to produce high-purity tritium water (HTO ₂ ).

FIG. 2 shows an embodiment that is a modification of the water electrolysis device of FIG. In FIG. 2, the electrolyzers 33 of three water electrolyzers are connected in cascade. The tritium-containing water from the tritium-containing water storage tank 31 is supplied to the electrolytic cell 33-1 of the first water electrolysis device, and the tritium-containing water in the electrolytic cell 33-1 is electrolyzed with electric power (kw) using natural energy. , a mixed gas of hydrogen and oxygen is generated from the negative electrode, and oxygen gas is generated from the positive electrode. By supplying the generated hydrogen gas and oxygen gas to the fuel cell, the fuel cell can generate electricity.

Tritium-containing water is supplied to the first electrolytic cell 33-1 of the first electrolyzer to electrolyze the tritium-containing water in the first electrolytic cell 33-1, and the tritium-containing water at the bottom of the first electrolytic cell is 2 The tritium-containing water in the second electrolytic cell 33-2 is electrolyzed by supplying it to the second electrolytic cell 33-2 of the electrolyzer 2, and the tritium-containing water at the bottom of the electrolytic cell of the preceding electrolytic cell is The tritium-containing water in the third electrolytic cell 33-3 is electrolyzed by supplying it to the electrolytic cell 33-3 of the electrolyzer. By taking out the tritium-containing water from the bottom of the electrolytic cell of the final-stage electrolyzer, the volume of the tritium-containing water can be reduced by the effect of electrolysis in the final stage. It works favorably for the volume reduction business of tritium-containing water.

Since tritiated water has a higher specific gravity than water, highly concentrated lithium water tends to accumulate at the bottom of the electrolytic cell. The tritium concentration of the tritium-containing water increases each time it moves from the bottom of each electrolyzer to the next electrolyzer to the downstream electrolyzer. By cascade-connecting the electrolytic cells of the water electrolysis device in this manner, the tritium concentration of the tritium-containing water increases, and the volume of the tritium-containing water can be reduced.

If, instead of the separation device 24 shown in FIG. 1, three separation devices 41-1, 41-2, and 41-3 are connected in series as shown in FIG. Improvement can be expected. Gas containing tritium from the hydrogen tank 20 is sent to the separator 40 . The purity of tritium improves as it passes through the special separators 41-1, 41-2, and 41-3.

The method and commercialization of removing tritium from tritium-containing water will be described below. That is, the inventor devised a method of rendering tritium-containing water harmless and selling the removed tritium, and commercializing the method.

Tritium-containing water is received from a power plant for a fee or free of charge, and the tritium-containing water is electrolyzed using electricity from the power plant that uses natural energy. Gas and hydrogen gas are separated, and tritium gas is compressed and sold. Oxygen gas generated by water electrolysis and the tritium gas are burned and sold as tritiated water. Oxygen gas generated by water electrolysis and hydrogen gas generated by the separator are led to the fuel cell, and the power generated by the fuel cell is sold.

Let us calculate a rough estimate of the profit when commercialization is carried out using the tritium-containing water treatment apparatus of the embodiment of the present invention. The unit price of natural energy is 20 yen/kWh, the normal selling price of fuel cells is 24 yen/kWh, the selling price of high-output fuel cells is 100 yen/kWh, and the unit price of tritium gas is 100 yen/kWh. kWh, the profit per unit is 142 yen/kWh. Assuming that the operating rate of 100 MW natural energy power generation is 20%, the annual power consumption is 20 MW x 24 h x 365 days = 175,200 MWh/year. If the tritium-containing water is collected for a fee, the profit will be further increased.

The commercialization of receiving tritium-containing water from nuclear power plants on the condition that the volume of tritium-containing water is reduced, reducing the volume of tritium-containing water by water electrolysis, and returning it to customers or disposing of it depends on the power plant side and The transaction will be beneficial for both parties. Since the volume of tritium-containing water is reduced, there is an advantage for the customer, and if tritium is separated from the tritium-containing water and sold, it is also an advantage for the trader.

In the supply and demand of electric power, the generated electric power and the consumed electric power must be in balance. However, electric power generated by photovoltaic power generation and wind power generation using natural energy may disturb the electric power system. Since power generation using natural energy depends on natural conditions, power may not be supplied when power is needed, and power may be generated when power is not needed. By utilizing the tritium-containing water treatment method of the embodiment of the present invention, the supply and demand of electric power can be adjusted.

When there is a surplus of power in the system, the water electrolysis device is operated to temporarily store the hydrogen gas and oxygen gas generated by water electrolysis of the tritium-containing water. When power demand increases and a power shortage occurs, if the fuel cell is operated using the hydrogen gas and oxygen gas stored during the power surplus, the power of the fuel cell can compensate for the shortage of power demand. In this way, power generation using natural energy can be utilized without wasting it.

In the conventional fuel cell, since the gas diffusion electrode, the line where the gas, the liquid and the solid are in contact at the same time, is used as the reaction space, the reaction space is small and the reaction speed is slow. Poor readiness when power shortage occurs. However, in the case of a fuel cell storage battery, electrical energy can be taken out as a secondary battery during discharge, so rapid discharge is possible and load followability can be improved.

Fuel cell accumulators differ from conventional fuel cells in that their electrodes are coated with an active material. The electrode itself may be the active material. The negative electrode contains a hydrogen storage alloy and the positive electrode contains manganese hydroxide. A potassium hydroxide aqueous solution is held in the separator.

When the current is continued to be supplied after the electrodes of the fuel cell storage battery are initially charged, hydrogen gas is generated from the negative electrode and oxygen gas is generated from the positive electrode. Hydrogen gas is stored in the hydrogen storage compartment and oxygen gas is stored in the oxygen storage compartment.

During discharge of the fuel cell storage battery, a discharge reaction occurs between the negative electrode and the positive electrode. This causes current to flow through the external circuit. At this time, the amount of electricity in the negative electrode and the positive electrode decreases due to discharge. The reduced amount of electricity in the negative electrode and positive electrode is compensated by charging with hydrogen gas and oxygen gas stored in the hydrogen storage chamber and oxygen storage chamber. Thereby, the charged state of the negative electrode and the positive electrode is maintained.

If a stacked secondary battery is connected to a fuel cell or a fuel cell storage battery and electric power from this stacked secondary battery is sold, responsiveness can be further increased. A laminated secondary battery, which will be described later, has excellent cooling performance, and thus can be charged and discharged at a large current. It is possible to respond to emergency power shortages, which increases convenience and works in favor of power sales.

The laminated type secondary battery 1 shown in FIG. 4 includes, as main constituent elements, an exterior body 5, a collector rod 7, and an electrode body 3 housed inside the exterior body. The exterior body 5 is composed of a bottomed cylindrical can 2 and a disk-shaped lid member 6 attached to the opening 2c of the cylindrical can. After housing the electrode body 3, the lid member 6 is tightly fitted in the opening 2c of the cylindrical can. A closed structure is ensured.

An electrode body 3 composed of a positive electrode 3a, a negative electrode 3b, and a separator 3c interposed between the positive electrode 3a and the negative electrode 3b is laminated in the axial direction of the cylindrical can 2 (X direction in FIG. is housed inside the The outer edge 3ab of the positive electrode is in contact with the inner surface 2a of the cylindrical can, and the positive electrode 3a and the cylindrical can 2 are electrically connected. A collector rod 7 penetrates through the center of the electrode body 3 . A peripheral edge portion 3ba of the hole of the negative electrode is in contact with the shaft portion 7a, and the negative electrode 3b and the collector rod 7 are electrically connected.

Since the outer diameter of the negative electrode 3b is slightly larger than the inner diameter of the cylindrical can 2, the negative electrode 3b is strongly pressed against the cylindrical can 2 and is in close contact. The heat generated at the negative electrode 3b is transferred directly to the cylindrical can 2. Moreover, the heat generated at the positive electrode 3a is transmitted to the negative electrode 3b through the separator 3c. The separator 3c does not conduct heat easily, but since it is thin and has only one sheet, it does not significantly hinder the conduction of heat. As described above, the heat generated by the electrodes 3a and 3b is transmitted to the cylindrical can 2 with a small thermal gradient. Since the heat generated inside the battery is quickly released to the outside, it is possible to suppress the temperature rise inside the laminated type secondary battery.

The tritium-containing water treatment business according to the present invention can be suitably used as an industrial business.

1 Laminated Secondary Battery 2 Cylindrical Can 3 Electrode Body 4 Insulating Plate 5 Exterior Body 6 Lid Member 7 Current Collector 10 Exterior Body 11 Negative Electrode Terminal 13 Electrolytic Solution 14 Negative Electrode 15 Separator 16 Positive Electrode 17 Insulating Member 18 Hydrogen Storage Chamber 19 Oxygen Storage Chamber 20 Tritium-containing water treatment device 21 Water electrolysis device 22 Hydrogen tank 23 Oxygen tank 24 Separation device 25 Fuel cell 26 Tritium tank 27 Hydrogen chamber 28 Combustion chamber 30 External power supply 31 Tritium-containing water storage tank

Claims (13)

Wastewater containing tritium is collected for a fee, the wastewater is subjected to water electrolysis using electricity obtained from natural energy, and tritium gas and hydrogen gas are separated from the hydrogen-containing gas obtained by the water electrolysis. , a tritium-containing water treatment business that sells said tritium gas. 2. The business of treating tritium-containing water according to claim 1, wherein the oxygen gas obtained by the water electrolysis and the tritium gas are reacted to produce and sell tritiated water. 3. The business of treating tritium-containing water according to claim 1, wherein the hydrogen gas is supplied to a fuel cell and the electric power from the fuel cell is sold. The tritium-containing water treatment business according to any one of claims 1 to 3, wherein the water electrolysis is performed in cascade. The tritium-containing water treatment business according to any one of claims 1 to 4, wherein the tritium gas and hydrogen gas are separated in multiple stages. The tritium-containing water treatment business according to any one of claims 1 to 5, wherein the water generated by the power generation of the fuel cell is treated as water supply or waste water. The tritium-containing water treatment business according to any one of claims 1 to 5, wherein the tritium gas is compressed and sold. The tritium-containing water treatment business according to any one of claims 1 to 6, wherein the fuel cell is a fuel cell storage battery. 9. The business of treating tritium-containing water according to claim 8, wherein power of said fuel cell or secondary battery connected to said fuel cell storage battery is sold. 10. The secondary battery has doughnut-shaped electrodes stacked, wherein the outer edge of one of the electrodes is electrically connected to the exterior body and the edge of the hole of the other electrode is electrically connected to the current collector. Treatment of tritium-containing water described in . Wastewater containing tritium is collected for a fee, water electrolysis is performed on the wastewater using electricity obtained from natural energy, and tritium gas and hydrogen gas are separated from the hydrogen-containing gas obtained by the water electrolysis. The oxygen gas obtained by the water electrolysis is reacted with the tritium gas to produce tritiated water, and the hydrogen gas and the oxygen gas are supplied to a fuel cell to generate power from the fuel cell. Method. A water electrolysis device for electrolyzing water containing tritium and a separation device for separating tritium gas and hydrogen gas generated from a cathode of the water electrolysis device, wherein the hydrogen gas and the water separated by the separation device A tritium-containing water treatment apparatus equipped with a fuel cell that generates electricity using oxygen gas generated from the anode of an electrolyzer. 13. The apparatus for treating tritium-containing water according to claim 12, wherein a plurality of said water electrolysis apparatuses are cascade-connected, and said separation apparatus according to claim 12 is configured in multiple stages.

Images