JP2010064074A - Method and apparatus for treating ammonia-containing regeneration waste liquid from condensate demineralizer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide equipment for separating and decomposing ammonia formed from a reductive nitrogen compound in a plant where the reductive nitrogen compound is injected to inhibit corrosion of structural materials in a nuclear reactor. <P>SOLUTION: There is provided a method for treating an ammonia-containing regeneration waste liquid discharged when a condensate demineralizer in a nuclear power plant is regenerated, which includes the steps of: adding an alkali to the ammonia-containing regeneration waste liquid discharged; separating ammonia in the vapor phase by aeration under heating; and decomposing the formed ammonia gas with a catalyst. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for treating an ammonia-containing reclaimed waste liquid discharged during the regeneration process of a condensate demineralizer used to purify the condensate of a nuclear power plant, and an apparatus therefor.

  Nuclear power generation generates electricity by converting water into steam in a reactor pressure vessel and rotating the turbine with the generated steam.

  A typical boiling water nuclear power plant is shown in FIG. In the boiling water nuclear power plant, a condensate cooler 12, a condensate demineralizer 3, a feed water pump 4, a feed water heater 5, and a reactor pressure vessel 1 loaded with nuclear fuel are connected by a feed water system pipe 6, and the reactor pressure is increased. A closed loop is formed by connecting the vessel 1 and the turbine 2 with a main steam pipe 13. Water is used as the reactor coolant, water is made steam in the reactor pressure vessel 1, the turbine is rotated using the steam, and a generator (not shown) is rotated to generate power. The steam is returned to water by the condensate cooler 12, impurities are removed by the condensate filtration demineralizer 3, and finally returned to the reactor pressure vessel 1 through the feed water heater 5 by the feed water pump 4.

  During plant operation, the reactor cooling water becomes hot (in the present invention, the temperature at 100 ° C or higher is high, and the core outlet temperature at the rated power operation is 288 ° C), and the radiation is decomposed by the action of strong gamma rays and neutron rays in the core. Several hundreds of ppb of oxygen and hydrogen peroxide, which are decomposition products, are produced. The structural material (stainless steel, nickel-base alloy) constituting the reactor internal structure and pressure boundary is exposed to high-temperature reactor cooling water containing such a radiolysis product.

  In order to reduce oxygen, hydrogen peroxide, and the like in the reactor cooling water, a method is known in which hydrogen is injected to reduce hydrogen peroxide, oxygen, and the like (Japanese Patent No. 2865726).

  In addition, as a method for reducing oxygen, hydrogen peroxide, and the like in the reactor cooling water, a method of injecting hydrogen and a reducing nitrogen compound (for example, hydrazine) into the reactor water has been proposed (JP 2005-2005). 43051). This method is attracting attention as a future technology for improving the reactor water environment because it suppresses an increase in the dose of the turbine system and can reduce the oxidant concentration in the entire reactor water.

  When hydrazine is injected into the reactor, it reacts with oxygen and hydrogen peroxide as shown in Equations 1 and 2 to form nitrogen molecules and water that do not affect pH and conductivity, thus reducing the oxidant concentration in the reactor water. It becomes possible to do. Hydrazine has a higher reaction rate with oxygen and hydrogen peroxide than hydrogen, and reacts quickly into nitrogen and water.

N ₂ H ₄ + O ₂ → N ₂ + 2H ₂ O Formula 1
_{N 2 H 4 + 2H 2 O} 2 → N 2 + 4H 2 O ··· Equation 2
By the way, when hydrazine is irradiated with γ rays, the reaction of Formula 3 occurs to release ammonia and hydrogen in addition to nitrogen.

N ₂ H ₄ → NH ₃ + (1/2) N ₂ + (1/2) H ₂ Formula 3
When a reducing nitrogen compound such as hydrazine is injected in this way, a very small amount of ammonia is generated and distributed in the plant.

  As a method for removing ammonia from the waste liquid, for example, a method is known in which ammonia gas is vapor-phase separated by adding alkaline chemicals to the ammonia-containing waste liquid to bring the pH to 10 or more (for example, Japanese Patent Laid-Open No. Hei 10-10). 5947, JP-A-11-347535). Furthermore, a method is known in which ammonia in waste liquid is effectively transferred to the gas phase by spraying ammonia-containing waste liquid into the atmosphere to increase the contact area between the waste liquid and air (for example, Japanese Patent Laid-Open No. 2001-2001). -104943, JP-A-10-5747). The gas phase separated ammonia gas is brought into contact with a hypobromite solution and decomposed (for example, JP-A-7-31966), a direct combustion method (JP-A-7-11665), and a thermal decomposition method using a catalyst. (For example, JP-A-11-347535) and the like.

  As described above, when a reducing nitrogen compound (hydrazine or the like) is injected in a nuclear power plant, a small amount of ammonia is generated as a by-product. Ammonia generated in the nuclear reactor is transferred to the turbine together with steam, and is dissolved again in condensed water (hereinafter referred to as condensate) by the condenser.

  Ammonia dissolved in the condensate is adsorbed by an ion exchange resin of a condensate demineralizer provided for removing corrosive organisms and impurities in the condensate and removed from the condensate. Generally, the ion exchange capacity of the condensate demineralizer used in nuclear power plants is very large, and it can be used continuously for a long time from the viewpoint of ion exchange capacity. Since it is necessary to efficiently remove substances and impurities, and a high level of ion exchange capacity must be maintained at all times, the ion exchange resin of the condensate demineralizer must be periodically regenerated. .

  The regeneration treatment of the ion exchange resin is performed by chemically washing the ion exchange resin with a chemical cleaning solution. Ammonia adsorbed on the ion exchange resin is transferred into a chemical cleaning waste liquid (hereinafter also referred to as “regenerated waste liquid” or “regenerated water”) by chemically cleaning the ion exchange resin. The recycled waste liquid is concentrated and reduced in volume by evaporating water, and the concentrated waste liquid is mixed with cement or other solidifying material and stabilized.

  On the other hand, the evaporation fraction of the regenerated waste liquid contains water and ammonia, and this is returned to the liquid again by the condenser. This condensed water is finally further treated with an ion exchange resin or the like in order to remove ammonia and other impurities.

  If the ammonia content in the recycled wastewater (condensed water) is high, the amount of ion exchange resin required for the removal will also increase. Although this used ion exchange resin is processed as radioactive waste, it takes time and effort to process the radioactive waste, and it is important to reduce the amount of generated radioactive waste.

  Examples of the method for treating the ammonia-containing waste liquid include the methods described in JP-A Nos. 7-110466, 7-275896, and 8-39081. However, for the purpose of reducing the amount of radioactive waste generated, there is no known method for efficiently removing ammonia from the regenerated waste liquid discharged during the regeneration of the desalinator of a nuclear power plant.

Japanese Patent Application Laid-Open No. 7-100466 JP 7-275896 A JP-A-8-39081

As described above, in the treatment of the reclaimed waste liquid from the desalinator of the nuclear power plant, the problem is that a large amount of ion exchange resin used for removing ammonia in the regenerated waste liquid is generated as radioactive waste. It was.
An object of the present invention is to provide a method capable of efficiently removing ammonia in the regenerated waste liquid and reducing the generation amount of radioactive waste in the treatment of the regenerated waste liquid from the desalter of the nuclear power plant. And

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention treated the regenerated waste liquid with an alkali or treated it with an electric regenerative pure water device to cause ammonia in the regenerated waste liquid to be vapor-phase separated. The present invention has been completed by finding that the amount of radioactive waste that can be safely and simply processed and that is troublesome and expensive to process can be greatly reduced.

That is, the present invention includes the following inventions.
(1) A method for treating ammonia-containing reclaimed waste liquid discharged during regeneration of a condensate demineralizer in a nuclear power plant, comprising adding alkali to the discharged ammonia-containing reclaimed waste liquid, and ventilating the air under heating The method comprising the steps of gas phase separation of ammonia and the step of decomposing the generated ammonia gas with a catalyst.
(2) The method according to (1), wherein the pH of the recycled waste liquid is adjusted to 11 to 12.5 in the alkali addition step.
(3) The method according to (1) or (2) above, wherein the recycled waste liquid is heated to 60 ° C. or higher.
(4) The method according to any one of (1) to (3), further including a step of adjusting the pH of the regenerated waste liquid to 5 to 9 by adding an acid after setting the ammonia concentration in the regenerated waste liquid to 1 ppm or less. Method. (5) The step of decomposing ammonia gas separated by gas phase with a catalyst is carried out at 250 to 300 ° C. with the supply rate of ammonia gas per hour being 1/15000 or less of the catalyst volume. The method according to any one of 1) to (4).
(6) A method for treating ammonia-containing reclaimed waste liquid discharged during regeneration of a condensate demineralizer in a nuclear power plant, wherein the discharged ammonia-containing reclaimed waste liquid is heated and evaporated, and the evaporated steam is cooled. The condensed water, the step of passing the condensed water through an electric regenerative pure water device equipped with an electrode and a cation exchange membrane to produce ammonia concentrated water on the cathode side, and the vapor phase separated ammonia gas Decomposing with a catalyst.
(7) The above (6), which comprises circulating ammonia concentrated water generated on the cathode side of the electric regenerative pure water device to the condensed water, thereby increasing the ammonia concentration in the condensed water and separating ammonia in a gas phase. the method of.
(8) The method according to (6) or (7) above, comprising aerating air to the condensed water and / or heating the condensed water.
(9) The step of decomposing ammonia gas separated by gas phase with a catalyst is carried out at 250 to 300 ° C., wherein the supply rate of ammonia gas per hour is set to 1/15000 or less of the catalyst volume. The method according to any one of 6) to (8).
(10) A treatment apparatus for ammonia-containing reclaimed waste liquid discharged during the regeneration of a condensate demineralizer in a nuclear power plant, and a recovery tank for receiving the discharged ammonia-containing reclaimed waste liquid, and addition to the reclaimed waste liquid in the recovery tank Tank for storing the alkali to be recovered, a heating device for heating the regenerated waste liquid in the recovery tank, a device for ventilating the regenerated waste liquid in the recovery tank, and a catalyst for decomposing ammonia gas separated from the regenerated waste liquid in a gas phase And said device.
(11) A treatment apparatus for ammonia-containing reclaimed waste liquid discharged during regeneration of a condensate demineralizer in a nuclear power plant, which heats and discharges the steam from the ammonia-containing reclaimed waste liquid discharged from the heating evaporator A condensing water tank for receiving condensed water from the condenser, an electric regenerative pure water device for generating ammonia concentrated water from the condensed water, and a catalyst for decomposing gas phase separated ammonia gas Said device.
(12) The apparatus according to (11), wherein a pipe is provided so that the concentrated ammonia water generated by the electric regenerative pure water apparatus is circulated to the condensed water tank.

  By treating the regenerated waste liquid discharged during the regeneration of the ion exchange resin in the condensate demineralizer of a nuclear power plant with an alkali or electric regenerative pure water device, the ammonia in the regenerated waste liquid is separated in a gas phase, thereby Thus, the amount of ion exchange resin that has been used in large quantities for the removal of ammonia can be reduced, thereby greatly reducing the amount of radioactive waste generated and the cost of disposal.

It is a schematic diagram of a boiling water nuclear power plant. It is a figure which shows the relationship between the pH, temperature, air aeration in the simulation reproduction | regeneration waste liquid containing ammonia, and the ammonia residual concentration in a reproduction | regeneration waste liquid. It is a figure which shows the structure of an electric regeneration type | formula pure water apparatus. It is a figure which shows the ammonia gas decomposition | disassembly test result by a catalyst. It is a figure which shows the structure of the chemical | drug | medicine regeneration apparatus of a condensate demineralizer ion exchange resin, and the evaporation concentration apparatus of a regeneration waste liquid. 1 is a diagram illustrating a configuration of an apparatus used in Example 1. FIG. It is a figure which shows the structure of the apparatus used in Example 2. FIG. It is a figure which shows the structure of the apparatus used in Example 3. FIG.

  Fig. 5 shows an ion exchange resin regeneration facility, a regeneration waste liquid treatment facility (waste treatment system) for a condensate demineralizer in a general nuclear power plant (boiling water nuclear plant), and an ion exchange resin regeneration method. Illustrated.

  The condensate flows through the condensate pipe 32 to the condensate demineralizer 3 composed of a plurality of demineralizers, and the corrosion products in the condensate etc. by the ion exchange resin and the like provided in the condensate demineralizer 3 Impurities are removed. When the ion exchange resin in the condensate demineralizer deteriorates due to corrosion product adsorption or the like and its purification performance is reduced, the desalting tower is disconnected from the condensate system and the ion exchange resin is regenerated. Since the condensate demineralizer is filled with a mixture of a cation resin and an anion resin, regeneration of the ion exchange resin is performed by separating the cation resin and the anion resin. First, the ion exchange resin is transferred from the desalter 3 to the ion exchange resin separation / cation resin washing tower 21 through the pipe 33. In the ion exchange resin separation / cation resin washing tower 21, an anion resin having a small specific gravity is separated into an upper layer and a cationic resin having a large specific gravity is separated into a lower layer. The upper layer anion resin is sent to the anion resin regeneration tower 22 via the pipe 34. The cation resin is left as it is in the ion exchange resin separation / cation resin washing tower 21 and is supplied with sulfuric acid as a regenerative chemical from the sulfuric acid storage tank 24. The sulfuric acid from which the cationic resin has been washed is collected in the chemical washing waste liquid (recycled waste liquid) collection tank 26 via the pipe 40. Similarly, caustic soda is sent to the anion resin regeneration tower 22 from the caustic soda storage tank 25. The caustic soda used for the regeneration of the anion resin is recovered in the regeneration waste liquid recovery tank 26. The ion exchange resin regenerated with sulfuric acid and caustic soda is washed with water, then transferred to the resin storage tank 23 via the pipes 35 and 36, mixed, returned to the condensate demineralizer 3 via the pipe 37, The regeneration operation of the ion exchange resin is completed.

  The reclaimed waste liquid in the reclaimed waste liquid recovery tank is sent to the evaporative concentrator 27, heated to the boil, and separated into steam and a chemical cleaning chemical concentrate. The concentrated chemical cleaning chemical is sent to a waste solidification facility (not shown), mixed with a solidification material such as cement, and filled into a drum. The vapor evaporated from the recycled waste liquid is cooled by the condenser 28 to become condensed water, and is recovered in the condensed water recovery tank 29. Next, the condensed water is sent to the low-conductivity waste liquid collection tank 30, purified again by the waste treatment system demineralizer 31, and stored in a makeup water storage tank (not shown) through the pipe 44.

  In the treatment method of the present invention, alkali is added to the ammonia-containing regeneration waste liquid discharged at the time of regeneration of the condensate demineralizer of the nuclear power plant, and the ammonia is vapor-phase separated by bubbling air under heating to this, It involves cracking the resulting ammonia gas with a catalyst.

  In order to vapor-separate ammonia from the recycled waste liquid, it is preferable to add an alkali stronger than ammonia. Examples of such alkalis include alkali metal hydroxides such as potassium hydroxide and sodium hydroxide, and alkaline earth metal hydroxides such as calcium hydroxide and magnesium hydroxide.

The present inventors examined the relationship between the amount of alkali added and the processing temperature and the amount of gas phase separation of ammonia. An alkali (NaOH) was added to an ammonia-containing test solution (containing sulfuric acid: 3.4%, NH ₄ : 480 ppm) simulating the regeneration waste liquid of the ion exchange resin, and the test solution was adjusted to a predetermined pH and temperature. The gas phase separation amount of ammonia gas was examined by measuring the NH ₄ concentration in the test solution. The result is shown in FIG.

From the results of FIG. 2, when the temperature of the test solution is 40 ° C. or 50 ° C., when the pH of the test solution is increased to 13, most of the ammonia (NH ₄ ⁺ ions, NH ₃ ) in the test solution is vaporized. It was found that the phases were separated and separated as ammonia gas. When the temperature of the test solution is 60 ° C., the pH of the test solution is raised to 12.5, so that ammonia in the test solution can be separated in a gas phase. Furthermore, it was found that ammonia can be sufficiently vapor-phase separated at a pH of 11 or more by simultaneously performing an operation of bubbling air through the recycled waste liquid. However, at 25 ° C. or lower, the gas phase separation amount of ammonia gas did not increase so much even when the pH was raised.

  The regenerated waste liquid after separating ammonia is usually evaporated and concentrated, but in order to suppress corrosion due to alkali in the evaporative concentrator, it is necessary to neutralize the waste liquid before sending it to the evaporative concentrator with an acid. is there. For this reason, after alkali is added to the regenerated waste liquid and ammonia is vapor-phase separated, an acid such as sulfuric acid is added to the waste liquid to neutralize the pH of the waste liquid in the range of 5 to 9, preferably 8 to 9. .

  By the way, the added alkali and acid are concentrated in a later evaporation and concentration step and discarded as radioactive waste. However, if the amount of added alkali is large, the amount of acid added necessary for neutralization is also large. As a result, the amount of radioactive waste increases, so it is preferable to reduce the amount of alkali added to the recycled waste liquid as much as possible. As can be seen from the results of FIG. 2, when the treatment temperature of the regenerated waste liquid is set to 60 ° C. and the air is bubbled, the regenerated solution has a pH of 13 or less, preferably even when the pH is 11 to 12.5. Gas can be separated in a gas phase, and the amount of alkali added can be reduced.

  The ammonia concentration in the regenerated waste liquid before treatment is usually 100 to 500 ppm, but the ammonia concentration in the regenerated waste liquid is greatly reduced by the alkali treatment as described above. In the present invention, the ammonia concentration in the recycled waste liquid is preferably 1 ppm or less.

  Furthermore, the present invention is a method for heating and evaporating ammonia-containing regenerated waste liquid discharged at the time of regeneration of a condensate demineralizer in a nuclear power plant by evaporating and concentrating the evaporated vapor to condensate, which is used as an electrode. Provided is a method for treating a regenerated waste liquid, which comprises producing ammonia concentrated water on the cathode side through an electric regenerative pure water device equipped with a cation exchange membrane, and decomposing ammonia gas separated in a gas phase with a catalyst.

  In this method, the ammonia-containing regenerated waste liquid discharged during the regeneration of the condensate demineralizer is first separated into a concentrated waste liquid and an evaporative fraction waste liquid by an evaporative concentrator. Ammonia evaporates with water and moves to an evaporating fraction waste liquid. The evaporated regenerated waste liquid is cooled by a condenser to become condensed water, which is received in a condensed water tank. Next, the condensed water is energized through an electric regenerative pure water device equipped with a cation exchange membrane, thereby concentrating the ammonia component (ammonium ions) on the cathode side and increasing the ammonia concentration in the condensed water. Gas phase separation is performed.

  As shown in FIG. 3, the electric regenerative pure water apparatus is an apparatus in which a cation exchange membrane 18 is disposed between an anode 16 and a cathode 17. The cation exchange membrane has a property that allows a cation to easily pass therethrough but does not allow an anion to pass therethrough. When a DC voltage is applied to the anode and cathode of the electric regeneration type pure water device, ammonium ions present in the desalination chamber 19 on the anode side in the electric regeneration type pure water device are attracted to the cathode and pass through the cation exchange membrane. It moves to the concentration chamber 20, and ammonia concentrated water with an increased ammonia (ammonium ion) concentration is generated in the concentration chamber 20. When the ammonia concentration in the ammonia-concentrated water increases, ammonia is separated in the gas phase, and is captured and decomposed with a catalyst or the like.

  Preferably, a circulating operation is performed in which the concentrated ammonia water in the concentrating chamber 20 is returned to the condensed water tank and again passed through the electric regeneration type pure device. Thereby, the ammonia concentration in a condensed water tank can be raised efficiently.

  Furthermore, the efficiency of vapor phase separation of ammonia in the condensed water can be synergistically improved by aerating air and / or heating the condensed water in the condensed water tank.

  In the method using the electric regeneration type pure water device, there is no need to add chemicals such as alkali, and therefore, there is an advantage that an increase in the amount of waste can be suppressed.

The ammonia gas separated as described above is treated by a known method. Examples of the ammonia gas treatment method include thermal decomposition using a catalyst. The present inventors examined the relationship between the catalyst temperature or the ammonia gas supply amount and the ammonia decomposition ability using a platinum catalyst. When the platinum catalyst temperature is 200 ° C., ammonia is hardly decomposed, but the catalyst temperature It was found that ammonia gas was efficiently decomposed when heated to 250 ° C. Particularly, the ammonia concentration at the outlet of the catalyst tower is reduced to 0.1% or less by ventilating the catalyst with an ammonia gas supply rate (cm ³ / h) per hour being 1/15000 or less of the catalyst volume (cm ³ ). It was confirmed that it could be reduced.

  Suitably, when a noble metal catalyst such as platinum is used as the ammonia gas decomposition catalyst, the catalyst is heated to 220 to 350 ° C, preferably 200 to 300 ° C. Moreover, when performing using transition metal catalysts, such as copper and chromium, it is preferable that the temperature of a catalyst shall be 300-400 degreeC.

  By treating the ammonia-containing reclaimed waste liquid discharged during the regeneration of the condensate demineralizer of a nuclear power plant by the above method, the ammonia in the reclaimed waste liquid can be treated safely and simply, and the amount of radioactive waste generated can be reduced. It can be greatly reduced.

Example 1 Treatment of Recycled Waste Liquid by Addition of Alkaline As a first example, a method for vapor phase separation of ammonia in the regenerated waste liquid by adjusting pH in the regenerated waste liquid recovery tank (FIG. 6) will be described.

  A plant that injects a reducing nitrogen compound such as hydrazine to reduce oxygen, hydrogen peroxide, and the like generated in the reactor water also generates a small amount of ammonia as a by-product in addition to nitrogen and water. Ammonia is adsorbed by the ion exchange resin of the condensate demineralizer and removed from the reactor water. The ion exchange resin to which ammonia or the like has been adsorbed is washed and regenerated using sulfuric acid and caustic soda, and the waste liquid (regenerated waste liquid) is recovered in the recycled waste liquid recovery tank 26.

  Caustic soda is added from the caustic soda storage tank 25 to the reclaimed waste liquid in the reclaimed waste liquid recovery tank 26 in order to cause gas phase separation of ammonia in the regenerated waste liquid. The pH of the recycled waste liquid is confirmed by a pH meter 51 provided in the recycled waste liquid recovery tank 26, and caustic soda is added until the pH of the recycled waste liquid is in the range of 11 to 12.5.

  Next, the temperature of the recycled waste liquid is raised to 60 ° C. by the heater 46 provided in the recycled waste liquid recovery tank. At the same time, air is supplied (bubbled) from the air supply pipe 45 to the recycled waste liquid recovery tank to promote gas phase separation of ammonia.

  Ammonia separated in the gas phase in the space above the waste liquid recovery tank 26 is sent to the catalyst decomposition tower 48 by the fan 47. The catalyst decomposition tower 48 has a heater for heating the catalyst, and the catalyst is heated to a predetermined temperature. The temperature of the catalytic cracking tower is desirably set in the range of 250 ° C. to 300 ° C. in the case of a catalyst to which a precious metal such as platinum is attached, and 300 ° C. in the case of using a catalyst to which a transition metal such as copper and chromium is attached. To 400 ° C. is desirable. The catalyst decomposition tower outlet gas is cooled to 60 ° C. or less by the cooler 49 and then sent to the ventilation air conditioning system of the power plant.

  It is desirable to confirm whether or not the vapor phase separation of ammonia from the recycled waste liquid has been completed by sampling the recycled waste liquid in the recycled waste liquid recovery tank and measuring the ammonia concentration. Alternatively, it can be confirmed more simply by monitoring the change in the catalyst decomposition tower outlet temperature. This is because when ammonia decomposes in the catalytic cracking tower, the temperature of the catalytic cracking tower exit is high while the ammonia is generated. This is because the temperature decreases.

  After the separation of the ammonia in the recycled waste liquid recovery tank is completed, the recycled waste liquid is sent to the evaporative concentrator 27. However, since the pH of the recycled waste liquid is high (strongly alkaline), the evaporative concentrator may be corroded. The acid is neutralized by adding acid to the recycled waste liquid before sending it to the evaporative concentrator. In this embodiment, sulfuric acid is added as an acid from the sulfuric acid storage tank 24 via the pipe 42 to the recycled waste liquid. At this time, the pH of the recycled waste liquid is adjusted to be in the range of 8-9 while confirming the indicated value of the pH meter 51 of the waste liquid recovery tank. The regenerated waste liquid whose pH is adjusted is transferred to the evaporative concentrator 27, where evaporative concentration treatment is performed, and is sent to a downstream waste liquid treatment step.

Example 2: Electrical as processing a second embodiment of a regenerative by reproducing effluent pure water apparatus, a method for vapor phase separation of ammonia from the condensate after evaporation process the regeneration effluent (Fig. 7).

  A plant that injects a reducing nitrogen compound such as hydrazine to reduce oxygen, hydrogen peroxide, and the like generated in the reactor water also generates a small amount of ammonia as a by-product in addition to nitrogen and water. Ammonia is adsorbed by the ion exchange resin of the condensate demineralizer and removed from the reactor water. The ion exchange resin to which ammonia or the like has been adsorbed is washed and regenerated using sulfuric acid and caustic soda, and the waste liquid (regenerated waste liquid) is recovered in the recycled waste liquid recovery tank 26.

  The recycled waste liquid is transferred from the recycled waste liquid recovery tank 26 to the evaporation concentrator 27. The recycled waste liquid is sent to the heater 53 by the circulation pump 52 and heated. At the same time, the inside of the concentrator is decompressed by the vacuum pump 57 installed via the condenser 55. When the inside of the evaporation concentrator reaches a predetermined temperature and pressure, the regenerated waste liquid boils, water evaporates, and the waste liquid is concentrated. Since ammonia is volatile, it evaporates with the vapor, condenses with water in the condenser 55, and dissolves again in the condensed water. The condensed water in which ammonia is dissolved is collected in the condensed water tank 29.

  The condensed water is transferred to the electric regenerative pure water device 60 via the pipe 59. The electric regeneration type pure water apparatus includes a cation exchange membrane 18 between the anode 16 and the cathode 17. The cation exchange membrane has a property that allows a cation to easily pass therethrough but does not allow an anion to pass therethrough. When a direct current is supplied from the DC power source 61 to the anode and cathode of the electric regeneration type pure water device, ammonium ions on the anode side (desalting chamber) of the electric regeneration type pure water device move to the cathode side (concentration chamber). The desalination chamber water from which ammonium ions have been removed is collected in a low-conductivity waste liquid collection tank (not shown) via a pipe 62.

  On the other hand, the water on the cathode side (concentration chamber) in which ammonia has been concentrated is transferred again to the condensed water tank 29 via the pipe 63. In this way, when the circulation operation of returning the ammonia concentrated water generated on the cathode side to the condensate water tank 29 is repeated, the ammonium ion concentration of the regenerated waste liquid in the condensate water tank is increased, and as a result, the pH rises and the natural concentration increases. Ammonia is vapor phase separated.

  Ammonia separated in the vapor phase in the space above the condensed water tank 29 is sent to the catalyst decomposition tower 48 by the fan 47. The catalyst decomposition tower 48 has a heater for heating the catalyst, and heats the catalyst to a predetermined temperature. The temperature of the catalytic cracking tower is preferably set in the range of 250 ° C. to 300 ° C. in the case of a catalyst to which a precious metal such as platinum is attached, and 300 ° C. in the case of using a catalyst to which a transition metal such as copper and chromium is attached. To 400 ° C. is desirable. The catalyst decomposition tower outlet gas is cooled to 60 ° C. or less by the cooler 49 and then sent to the ventilation air conditioning system of the power plant.

Example 3 Treatment of Recycled Waste Using an Electric Regenerative Pure Water Device Combined with Heating or Air Aeration In the third example, the condensed water is heated in the condensed water tank 29 in the method shown in Example 2. In this method, air is ventilated to promote gas phase separation of ammonia (FIG. 8).

  The condensed water tank 29 is provided with an electric heater 46 for heating the condensed water and / or an air supply facility 45 for ventilating the condensed water, and the other devices used in the second embodiment (see FIG. Same as 7). By installing the electric heater 46 and / or the air supply equipment 45, the vapor phase separation efficiency of ammonia in the regenerated waste liquid can be remarkably improved. In addition, since the gas phase separation of ammonia and the operation method of the catalytic cracking facility are the same as those in Example 2, they are omitted.

DESCRIPTION OF SYMBOLS 1 Reactor pressure vessel 2 Turbine 3 Condensate demineralizer 4 Feed water pump 5 Feed water heater 6 Feed water system piping 7 Reactor cooling water recirculation pump 8 Reactor cooling water purification system pump 9 Reactor cooling water purification system piping 10 Atom Reactor cooling water purification system heat exchanger 11 Reactor cooling water filtration demineralizer 12 Condenser 13 Main steam pipe 21 Ion exchange resin separation and cation resin washing tower 22 Anion resin regeneration tower 23 Resin storage tank 24 Sulfuric acid storage tank 25 Caustic soda Storage tank 26 Recycled waste liquid recovery tank 27 Evaporative concentrator 30 Low-conductivity waste liquid collection tank 45 Air supply facility 46 Electric heater 47 Air supply fan 48 Catalytic decomposition tower 49 Cooler 51 pH meter 53 Evaporative concentrator heater 55 Evaporative concentration Condenser 57 Evaporative Concentrator Vacuum Pump 60 Electric Regenerative Pure Water Device

Claims (6)

  A method for treating ammonia-containing reclaimed waste liquid discharged during the regeneration of a condensate demineralizer in a nuclear power plant, a process of heating and evaporating the discharged ammonia-containing reclaimed waste liquid, and cooling and condensing the evaporated vapor A process of forming water, a process of generating condensed ammonia water on the cathode side by passing the condensed water through an electric regenerative pure water device equipped with an electrode and a cation exchange membrane, and decomposing ammonia gas separated by gas phase with a catalyst The method comprising the steps of:   The method according to claim 1, comprising circulating ammonia concentrated water generated on the cathode side of the electric regenerative pure water apparatus to the condensed water, thereby increasing ammonia concentration in the condensed water to separate ammonia in a gas phase.   3. A method according to claim 1 or 2, comprising aerating air to the condensed water and / or heating the condensed water.   4. The step of decomposing ammonia gas separated by a gas phase with a catalyst is performed at 250 to 300 ° C. with an ammonia gas supply rate per hour being 1/15000 or less of the catalyst volume. The method of any one of these.   An apparatus for treating ammonia-containing reclaimed waste liquid discharged during the regeneration of a condensate demineralizer of a nuclear power plant, which is a heating evaporator for the discharged ammonia-containing reclaimed waste liquid, and a condenser for cooling the vapor from the heat evaporator And a condensate tank for receiving condensate from the condenser, an electric regenerative pure water device for generating ammonia concentrated water from the condensate, and a catalyst for decomposing gas phase separated ammonia gas .   The apparatus according to claim 5, further comprising a pipe for circulating the ammonia concentrated water generated by the electric regenerative pure water apparatus to the condensed water tank.