JP2000334441A - Composite treatment of power plant waste water and composite treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively utilize the waste heat of each treated water and to suppress an increase in an apparatus manufacturing cost and apparatus running cost by executing the composite treatment of both of condensate desalting apparatus-regenerated waste water and flue gas desulfurization waste water when treating the former waste water by a catalytic wet process oxidation method and the latter waste water by an evaporation thickening method. SOLUTION: The condensate desalting apparatus-regenerated waste water 2 is treated by the catalytic web process oxidation method in a catalytic wet process oxidation apparatus 14 and the resulted catalytic wet process oxidation- treated water 16 is heat exchanged with the condensate desalting apparatus- regenerated waste water in a heat exchanger 10. The catalytic wet process oxidation-treated water is thereafter mixed with the flue gas desulfurization waste water 22 in an evaporation thickening apparatus 34 or a piping or an apparatus on the upstream side thereof. This water mixture is treated by the evaporation thickening method in the evaporation thickening apparatus and, thereafter, the resulted evaporation thickening treated water 36 is heat exchanged with the condensate desalting apparatus-regenerated waste water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combined treatment of a condensate desalination unit regeneration wastewater and a flue gas desulfurization wastewater discharged from a power plant.

[0002]

2. Description of the Related Art Wastewater generated at power plants includes condensate desalination unit regeneration wastewater and flue gas desulfurization wastewater. For example, in a thermal power plant, condensate is treated by a condensate treatment unit equipped with a condensate desalination device and then sent to the boiler again. An exchange device is used, and thus, when the ion exchange resin of the condensate desalination device is regenerated, the above-mentioned reclaimed water of the condensate desalination device is discharged. Further, in a thermal power plant using fuel oil or coal containing sulfur as a fuel, flue gas desulfurization treatment is performed for the purpose of preventing pollution, and the above-mentioned flue gas desulfurization wastewater is discharged from the flue gas desulfurization process. .

The above-mentioned reclaimed wastewater from the condensate desalination apparatus contains ammonia nitrogen at a high concentration, and the flue gas desulfurization wastewater contains high concentrations of sulfate ions and calcium ions as well as fluorine ions and heavy metal ions. Therefore, any wastewater must be treated, but new treatment methods have been proposed for these condensate and desalination unit regeneration wastewater and flue gas desulfurization wastewater due to recent development of wastewater treatment technology. . For example, a catalytic wet oxidation method has been proposed for the treatment of condensate desalination unit regeneration wastewater, and an evaporative concentration method has been proposed for the treatment of flue gas desulfurization wastewater. The details of the catalytic wet oxidation method and the evaporative concentration method will be described later.

[0004] Since both the catalytic wet oxidation method and the evaporative concentration method use heat for the treatment, these methods are devised for effective use of heat. That is, the treatment temperature of the catalytic wet oxidation method is usually about 100 to 370 ° C, preferably about 150 to 300 ° C, and the treatment temperature of the evaporative concentration method is about 50 to 100 ° C. In order to effectively use the waste heat of the treated water, the raw water (condensate demineralizer regeneration wastewater or flue gas desulfurized wastewater) is often preheated by the waste heat of the treated water via a heat exchanger.

Conventionally, in order to further effectively use the waste heat of the treated water of the condensate desalination unit regeneration wastewater by the catalytic wet oxidation method and the treated heat of the flue gas desulfurization wastewater by the evaporative concentration method, FIG.
The combined treatment of the condensate desalination equipment regeneration wastewater and flue gas desulfurization wastewater is performed by the apparatus shown in (1).

In FIG. 2, reference numeral 2 denotes a reclaimed drainage tank for a condensate desalination unit, 4 denotes a reclaimed drainage introduction pipe connected to the drainage tank 2, 6
Is a pump provided in the regeneration drain introduction pipe 4, 8 is a pH adjusting agent addition mechanism provided in the regeneration drain introduction pipe 4, 10 is a first heat exchanger connected to the regeneration drain introduction pipe 4, and 12 is a first heat exchanger. 1
The heater connected to the heat exchanger 10 of the
The treatment wet oxidation device (catalyst wet oxidation device) connected to the catalyst wet oxidation device 16 is connected to the catalyst wet oxidation treatment device 14 and is an outflow pipe of the catalyst wet oxidation treatment water. Reference numeral 22 denotes a flue gas desulfurization drainage storage tank; 24, a flue gas desulfurization drainage introduction pipe connected to the drainage storage tank 22; 26, a pump provided on the flue gas desulfurization drainage introduction pipe 24; , A second heat exchanger connected to the flue gas desulfurization drainage introduction pipe 24, and a second heat exchanger 30
Is an evaporating and concentrating treatment device (evaporating and concentrating device) connected to the heater 32; 36 is an evaporating and condensing water outlet pipe connected to the evaporating and concentrating device 34;
Denotes a concentrated liquid discharge pipe connected to the evaporating and concentrating device 34.
Further, in the apparatus of the present embodiment, the catalyst wet oxidation treated water outflow pipe 1
6 is connected to the flue gas desulfurization drainage introduction pipe 24 between the pH adjusting agent addition mechanism 28 and the second heat exchanger 30.

[0007] The combined treatment of the reclaimed wastewater and the flue gas desulfurization wastewater by the apparatus shown in FIG. 2 is performed as follows. That is, the condensed water desalination apparatus regeneration drainage in the condensate desalination apparatus regeneration drainage storage tank 2 is introduced into the first heat exchanger 10 by the operation of the pump 6. At this time, the pH adjusting agent addition mechanism 8
Thereby, a pH adjuster (alkali) is added to the wastewater flowing through the recycled wastewater introduction pipe 4, and the pH of the wastewater is adjusted to about 9 to 12. Next, the waste water is sequentially passed through the heater 12 and the catalytic wet oxidizer 14, and the catalytic wet oxidizer 14 removes ammonia nitrogen in the waste water at a high temperature of about 150 to 300 ° C. The high-temperature treated water (catalyst wet oxidized water) of the catalytic wet oxidizer 14 flows out of the catalyst wet oxidized water outlet pipe 16 and is condensed by the first heat exchanger 10 in a condensate desalination unit regeneration wastewater (raw water, usually About 20 ° C) and heat exchange,
It is mixed with the flue gas desulfurization wastewater flowing through the flue gas desulfurization wastewater introduction pipe 24. The exhaust gas generated by the catalytic wet oxidation device 14 is discharged from an exhaust gas outflow pipe (not shown).

Further, the flue gas desulfurization wastewater in the flue gas desulfurization wastewater storage tank 22 is introduced into the second heat exchanger 30 by the operation of the pump 26. At this time, a pH adjuster (acid or alkali) is added to the wastewater flowing through the flue gas desulfurization wastewater introduction pipe 24 by the pH adjuster addition mechanism 28, and the pH of the wastewater is adjusted so that the pH of the concentrated solution becomes weakly acidic to neutral. Is adjusted. Next, the waste water is sequentially passed through the heater 32 and the evaporative concentration device 34, and the evaporative concentration device 34 performs the evaporative concentration treatment of the waste water. The generated steam is condensed by the condenser of the evaporative concentrator 34, and the condensed water flows out to the evaporative concentrated water outlet pipe 36 as the evaporative concentrated water. This evaporatively concentrated water is subjected to heat exchange with flue gas desulfurization wastewater (raw water) in the second heat exchanger 30 and then discharged or reused. This evaporative concentration treated water is distilled water of relatively high purity. The concentrated liquid generated by the evaporating and concentrating device 34 is discharged from a concentrated liquid discharge pipe 38.

In the combined treatment using the apparatus shown in FIG. 2, the reclaimed wastewater from the condensate desalination unit is treated by the catalytic wet oxidation method, and then the catalytic wet oxidation treated water is mixed with the flue gas desulfurization wastewater, and the mixed water is evaporated. It is processed by the concentration method. In this combined treatment, not only the waste heat of the catalytic wet oxidation treatment water is used for preheating the condensate desalination equipment regeneration wastewater, and the waste heat of the evaporation concentrated treatment water is used for preheating the flue gas desulfurization wastewater, but also the catalytic wet Since the waste heat of the oxidized water is used for preheating the flue gas desulfurization wastewater, the waste heat of the treated water is more effectively used than when the reclaimed water and the flue gas desulfurization wastewater are treated separately. can do.

In the apparatus shown in FIG. 2, after treating the reclaimed wastewater from the condensate desalination apparatus with the catalytic wet oxidizer, the treated wet oxidized water and the condensate desalinizer regenerate through the first heat exchanger. The heat exchange with the wastewater is performed, but due to the decrease in the temperature of the catalytic wet oxidation water due to this heat exchange, rapid boiling when the pressure drops due to the catalytic wet oxidation water being mixed with the flue gas desulfurization wastewater at the subsequent stage is prevented. Is done.

[0011]

The flue gas desulfurization effluent has a property of being highly corrosive and easily causing scaling (precipitation of scale). Therefore, in the combined treatment apparatus shown in FIG. 2, the second heat exchanger 30 through which the flue gas desulfurization wastewater flows is passed.
It is necessary to use an expensive material such as high-grade stainless steel which is hardly corroded, which has been a factor of increasing the device manufacturing cost. In addition, if scaling occurs, it is necessary to perform chemical cleaning of the heat exchanger, so the installation of chemical cleaning equipment increases the equipment manufacturing cost, and the necessity of the cleaning work increases the equipment operating cost. I was The regenerated wastewater from the condensate desalination apparatus has low corrosiveness and is unlikely to be scaled, so that the first heat exchanger 10 does not have the above-described problems.

The present invention has been made in view of the above-mentioned circumstances. In treating condensate demineralizer regenerated wastewater by catalytic wet oxidation, and flue gas desulfurization wastewater by evaporative concentration, a combined treatment of both wastewaters is performed. It is an object of the present invention to provide a combined treatment method and a combined treatment device for power plant wastewater capable of effectively utilizing the waste heat of each treated water and suppressing an increase in device manufacturing cost and device operation cost. And

[0013]

In order to achieve the above object, the present invention provides a condensate desalination unit reclaimed wastewater by a catalytic wet oxidation method,
In treating the flue gas desulfurization wastewater by the evaporative concentration method, the condensate desalination unit regeneration wastewater is treated by the catalytic wet oxidation method, and the obtained catalyst wet oxidation treatment water is subjected to heat exchange with the condensate desalination unit regeneration wastewater. Mixing the catalyst wet oxidation treated water with flue gas desulfurization wastewater, treating this mixed water by the evaporative concentration method, and then heat-exchanging the obtained evaporated concentrated treated water with the condensate desalination unit regeneration wastewater. The present invention provides a combined treatment method for power plant wastewater.

Further, in order to achieve the above-mentioned object, the present invention provides a catalytic wet oxidizer for treating regenerated wastewater from a condensate desalination apparatus by a catalytic wet oxidation method, A regeneration wastewater introduction pipe to be introduced, first and second heat exchangers interposed in the regeneration wastewater introduction pipe, a catalytic wet oxidation treatment water discharge pipe through which treated water of the catalytic wet oxidation device flows, and flue gas desulfurization Evaporating and concentrating equipment that treats wastewater by the evaporative concentration method, a flue gas desulfurization wastewater introduction pipe that introduces flue gas desulfurization wastewater into the evaporative concentrator, and an evaporative concentration treated water outflow pipe through which treated water from the evaporative concentrator flows out. And, the first heat exchanger is interposed in the outflow pipe of the catalytic wet oxidation water, and the outflow end of the outflow pipe of the catalytic wet oxidation water is connected to the evaporative concentrator or a pipe or device upstream thereof. At the same time, the second heat exchanger To provide a composite processor power plants waste water, characterized in that it is interposed in the outlet pipe.

According to the present invention, the catalytic wet oxidized water having a high temperature is subjected to heat exchange with the regenerated wastewater of a condensate desalination apparatus having a low temperature, and the catalytic wet oxidized water having a reduced temperature due to the heat exchange. Is mixed with flue gas desulfurization wastewater, so that the waste heat of the catalytic wet oxidation treatment water and the evaporative concentration treatment water can be effectively used. In addition, flue gas desulfurization wastewater is not used for heat exchange, so it is only necessary to pass through the heat exchanger as reclaimed water from the condensate desalination equipment regeneration wastewater, which is weakly corrosive and less likely to cause scaling. There is no need to pass flue gas desulfurization wastewater, which is likely to occur. Therefore, it is not necessary to use an expensive material that is hardly corroded as the material of the heat exchanger, and it is sufficient to use general stainless steel or the like, so that it is possible to suppress an increase in apparatus manufacturing cost. In addition, scaling is unlikely to occur in the heat exchanger, and the necessity of installing chemical cleaning equipment and cleaning work can be eliminated, so that an increase in apparatus manufacturing cost and apparatus operating cost can be suppressed. Further, since the maintenance of the heat exchanger is facilitated, the operation cost of the apparatus can be reduced.

Hereinafter, the present invention will be described in more detail. In the present invention, the regenerated wastewater from the condensate desalination unit is treated by a catalytic wet oxidation method, and the flue gas desulfurization wastewater is treated by an evaporative concentration method. The condensate desalination apparatus regeneration wastewater is wastewater discharged when the ion exchange resin of the condensate desalination apparatus is regenerated. Flue gas desulfurization wastewater is wastewater discharged from a flue gas desulfurization process that performs desulfurization treatment of flue gas.

The catalyst wet oxidation treatment method is a method in which ammonia nitrogen in the water to be treated is oxidatively decomposed into nitrogen gas using an oxidizing agent in the presence of a catalyst. In the catalytic wet oxidation treatment method, generally, the water to be treated is heated to a predetermined temperature (usually 100 to 370 ° C.) in the presence of a metal catalyst, and the water to be treated is pressurized to a pressure for maintaining a liquid phase, and oxygen is added. A contained gas (for example, air) is supplied to the water to be treated as an oxidizing agent. As the catalyst, for example, silver, gold, platinum, cobalt,
A catalyst is used in which a catalyst component selected from nickel, palladium, rhodium, ruthenium, indium, iridium and their oxides, chlorides, sulfides and the like is appropriately supported on a carrier.

In the evaporative concentration method, the water to be treated is evaporated and concentrated using an evaporator, the generated steam is condensed, and condensed water is obtained as evaporative concentrated water. In general, the evaporative concentration processing is performed at a processing temperature of about 50 to 100 ° C. and a processing pressure of −670 to 670.
This is performed under the condition of about 0 mmHg. Usually, the pH of the water to be treated is adjusted so that the pH of the concentrated solution is weakly acidic to neutral. As the evaporator, for example, a horizontal heat transfer tube system, a vertical thin film system, or the like is used structurally, and an external heating system, a self vapor compression type, or the like is used as a heating system.

[0019]

Next, the present invention will be specifically described by way of embodiments. FIG. 1 is a flowchart showing an embodiment of a combined treatment apparatus for power plant wastewater according to the present invention. The apparatus shown in FIG. 1 is different from the apparatus shown in FIG. 2 in that the second heat exchanger 30 interposed in the evaporative concentration treated water outlet pipe 36 is connected to the flue gas desulfurization drain introduction pipe 2.
4 and installed between the pH adjusting agent addition mechanism 8 of the regeneration drain introduction pipe 4 and the first heat exchanger 10, and the outlet end of the catalyst wet oxidation treatment water outlet pipe 16 is disposed of flue gas desulfurization wastewater. The connection to the evaporating and concentrating device 34 without connecting to the introduction tube 24, and the provision of the pressure reducing valve 40 in the catalyst wet-type oxidized water outlet pipe 16 between the first heat exchanger 10 and the evaporating and concentrating device 34. Otherwise, it is similar to the device of FIG. Therefore, in FIG. 1, the same parts as those of the apparatus of FIG. 2 are denoted by the same reference numerals, and the description thereof will be omitted.

The combined treatment of the reclaimed wastewater and the flue gas desulfurization wastewater by the apparatus shown in FIG. 1 is performed as follows. That is, the regenerated condensate desalination device reclaimed wastewater in the condensate desalination device reclaimed drainage storage tank 2 is successively passed through the second heat exchanger 30 and the first heat exchanger 10 by the operation of the pump 6, and condensed. The heat exchange between the reclaimed wastewater from the desalination unit, the evaporatively-concentrated treated water, and the catalytic wet-oxidized treated water is sequentially performed to preheat the reclaimed condensate desalinated unit reclaimed wastewater. At this time, the pH of the wastewater is adjusted in the same manner as in the apparatus of FIG.

Next, the waste water is passed through a heater 12 and heated to, for example, about 150 to 300 ° C., and then passed through a catalytic wet oxidizer 14. Is removed. The high temperature catalytic wet oxidation water flows out to the catalyst wet oxidation water outlet pipe 16,
After performing heat exchange with the condensed water desalination equipment reclaimed wastewater (raw water) in the first heat exchanger 10 (the temperature of the catalytic wet oxidation treatment water is reduced to about 100 to 200 ° C. by this heat exchange), evaporation is performed. It is introduced into the concentration device 34 and mixed with the flue gas desulfurization wastewater in the piping of the evaporative concentration device 34 or in the evaporator. The exhaust gas generated by the catalytic wet oxidation device 14 is discharged from an exhaust gas outflow pipe (not shown).

In this case, the pressure of the catalytic wet oxidation water at the mixing point of the catalytic wet oxidation water and the flue gas desulfurization wastewater is:
When the pressure is extremely higher than the pressure of the flue gas desulfurization wastewater or the pressure inside the evaporator, it is preferable to reduce the pressure of the catalytic wet oxidation treatment water using the pressure reducing valve 40. This is because if a very large pressure difference is applied between the catalytic wet oxidation water and the flue gas desulfurization wastewater or the inside of the evaporator at the mixing point, a sudden boiling of the catalytic wet oxidation water occurs at the mixing point, and steam This is because an explosion may occur.

The flue gas desulfurization wastewater in the flue gas desulfurization wastewater storage tank 22 is introduced into the heater 32 by the operation of the pump 26,
It is heated to a predetermined temperature, for example, 70 ° C. At this time, the pH of the wastewater is adjusted in the same manner as in the apparatus of FIG. Next, the wastewater is introduced into the evaporative concentrator 34, where it is mixed with the catalytic wet oxidation treatment water as described above. The evaporating and concentrating device 34 performs evaporating and condensing treatment of the mixed water of the flue gas desulfurization wastewater and the catalytic wet oxidation treatment water, for example, at a temperature of 70 ° C. and a pressure of −530 mmHg. The treated water flows out to the evaporative concentrated treated water outflow pipe 36. The evaporatively-concentrated water has a temperature of, for example, about 50 ° C., and after being subjected to heat exchange with the condensate desalination apparatus regeneration wastewater (raw water) at approximately room temperature in the second heat exchanger 30, is discharged or reused. The concentrated liquid generated by the evaporating and concentrating device 34 is discharged from a concentrated liquid discharge pipe 38. The concentrate is further processed at a later stage, and heavy metals, COD
It is common to remove components and the like.

In the apparatus shown in FIG. 1, the outflow end of the catalytic wet oxidation treated water outflow pipe 16 is connected to the evaporative concentrator 34. The outflow end is connected to a pipe or apparatus upstream of the evaporative concentrator 34, for example, a drain. It may be connected to the smoke desulfurization drain introduction pipe 24 or the heater 32. Further, in the present invention, as described above, the temperature of the catalytic wet oxidized water passed through the first heat exchanger 10 is higher than the temperature of the evaporated concentrated water passed through the second heat exchanger 30. Since the temperature is generally higher depending on the temperature, the installation positions of the first and second heat exchangers are, as shown in FIG. 1, upstream of the first heat exchanger 10 through which the high-temperature catalytic wet oxidation water is passed. On the side, a second heat exchanger 30 by means of which low-temperature evaporatively-concentrated treated water is passed may be installed.

[0025]

EXAMPLE (Example) Using the apparatus shown in FIG. 1, combined treatment of the condensate desalination equipment regeneration wastewater and flue gas desulfurization wastewater of a coal-fired power plant was performed as described above. In this case, continuous processing was performed for 100 hours under the following processing conditions. As a result, even after 100 hours of continuous processing, the first
No scale was observed in the second heat exchanger, and the flow rate and temperature of the wastewater were stable. When the first and second heat exchangers were disassembled and inspected, no corrosion was observed and the material was sound.

The treatment conditions (1) device volume catalytic wet oxidation apparatus 0.05 m ³ evaporative concentration apparatus 0.05 m ³ (2) flow rate (manual adjustment in the degree of opening of the valve) condensate demineralizer regeneration effluent 1 m ³ / day waste smoke desulfurization effluent 1 m ³ / day evaporated treated water 0.95 m ³ / day concentrate 0.05m ³ / day ⁽³⁾ processing temperature catalytic wet oxidation treatment apparatus 170 ° C. evaporation apparatus 70 ° C. (pressure: -530mmHg) (4 ) Material of heat exchanger SUS316L (5) Wastewater quality Table 1 shows the results of water quality analysis of wastewater.

[0027]

[Table 1]

(Comparative Example) Using the apparatus shown in FIG. 2, the combined treatment of the condensate desalination unit regeneration wastewater and flue gas desulfurization wastewater was performed as described above. The processing conditions were the same as in the example. As a result, about 75 hours after the start of the treatment, the flow rate of the flue gas desulfurization effluent decreased, so the treatment was stopped. When disassembling the second heat exchanger and observing the inside, it was found that calcium scale was generated in the raw water side flow path and the flow path was partially blocked.

[0029]

According to the present invention, when treating the reclaimed wastewater of the condensate desalination apparatus by the catalytic wet oxidation method and the flue gas desulfurization wastewater by the evaporative concentration method, the combined treatment of both wastewaters is carried out, and the wastewater of each treated water is treated. The heat can be effectively used, and increase in device manufacturing cost and device operating cost can be suppressed.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating an embodiment of a combined treatment apparatus for power plant wastewater according to the present invention.

FIG. 2 is a flowchart showing an example of a conventional combined treatment apparatus for power plant wastewater.

[Explanation of symbols]

 2 Condensate demineralizer regeneration drainage storage tank 4 Regeneration drainage introduction pipe 10 First heat exchanger 12 Heater 14 Catalytic wet oxidizer 16 Catalytic wet oxidation treatment water outflow pipe 22 Flue gas desulfurization drainage storage tank 24 Flue gas desulfurization drainage introduction pipe Reference Signs List 30 second heat exchanger 32 heater 34 evaporative concentrator 36 evaporative concentration treated water outlet pipe 40 pressure reducing valve

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C02F 5/00 620 C02F 5/00 620B

Claims (4)

[Claims] In the treatment of reclaimed wastewater from a condensate desalination unit by a catalytic wet oxidation method and the treatment of flue gas desulfurization wastewater by an evaporative concentration method, the reclaimed wastewater from a condensate desalination unit is treated by a catalytic wet oxidation method. After heat exchange of the catalytic wet oxidation water with the condensate desalination unit regeneration wastewater, the catalytic wet oxidation water is mixed with the flue gas desulfurization wastewater, and this mixed water is treated by the evaporative concentration method, and the obtained evaporative concentration is obtained. A combined treatment method for power plant wastewater, wherein the treated water is heat-exchanged with a condensate desalination unit regeneration wastewater. 2. The power plant effluent according to claim 1, wherein the catalyst wet oxidized water is heat-exchanged with the condensate desalination unit regeneration wastewater, and then the catalyst wet oxidized water is decompressed and then mixed with the flue gas desulfurization wastewater. Complex processing method. 3. A catalytic wet oxidizer for treating the condensate demineralizer regeneration wastewater by a catalytic wet oxidation method, a regeneration drainage introduction pipe for introducing the condensate demineralizer regeneration wastewater to the catalytic wet oxidation device,
The first and second heat exchangers interposed in the regeneration drain introduction pipe, the catalytic wet oxidation treated water outflow pipe from which the treated water of the catalytic wet oxidation device flows out, and the flue gas desulfurization wastewater are treated by the evaporative concentration method. A first evaporative concentrator, a flue gas desulfurization wastewater introduction pipe for introducing flue gas desulfurization wastewater into the evaporative concentrator, and an evaporative condensed treated water outflow pipe from which treated water of the evaporative concentrator flows out;
Is disposed in the outflow pipe of the catalytically oxidized water, and the outflow end of the outflow pipe of the catalytically wet oxidized water is connected to the evaporative concentrator or a pipe or device upstream thereof, and the second heat exchanger A combined treatment device for power plant wastewater, characterized in that an exchanger is interposed in an evaporative concentration treated water outflow pipe. 4. The power plant drainage according to claim 3, wherein a pressure reducing valve is provided in the outflow pipe of the catalytically-oxidized water for treatment between the first heat exchanger and the evaporative concentrator or a pipe or apparatus upstream thereof. Complex processing equipment.