TW201706207A - Hypochlorous acid supply device and treatment method of boiler discharged water - Google Patents

Abstract

The present invention provides a hypochlorous acid supply device 1 including a storage vessel 5 which stores seawater M, an electrolysis device 2 which generates a hypochlorous acid containing liquid E by electrically decomposing the seawater M introduced from the storage vessel 5 and returns the obtained hypochlorous acid containing liquid E to the storage vessel 5, a supplying line 17 into which the hypochlorous acid containing liquid E stored in the storage vessel 5 is introduced, a reaction vessel 7 which reacts the hypochlorous acid containing liquid E supplied through the supplying line 17 and an ammonia containing boiler discharged water W, and injection lines 21 and 22 which inject a mixed liquid formed by mixing a treatment liquid T obtained by reaction in the reaction vessel 7 and the hypochlorous acid containing liquid E stored in the storage vessel 5.

Description

Hypochlorous acid supply device and method for treating boiler wastewater

The present invention relates to a hypochlorous acid supply device and a method for treating boiler wastewater, which are a device for supplying a hypochlorous acid-containing liquid generated from seawater to a plant utilizing hypochlorous acid and an ammonia-containing boiler wastewater.

This case is a priority of Japan's special offer 2015-085221, which was filed on April 17, 2015, and Japan's special offer 2015-202052, which was filed on October 13, 2015, and its contents are used.

For example, in a thermal power plant, hydrazine used to remove oxygen which is the main cause of corrosion is evaluated as a "chemical substance of a recognized mutant." Therefore, in recent years, safer oxygen scavengers or water treatments without using oxygen scavengers have been adopted.

As an oxygen scavenger which does not use hydrazine, ammonia having an increased hydrogen ion concentration index (pH) (for example, pH 7 to pH 10.5) is known. However, since ammonia is used as an oxygen scavenger, it is conceivable that the ammonia concentration of the plant wastewater will increase in the future (see, for example, Non-Patent Document 1). On the other hand, according to the wastewater regulations, it is also required to Low nitrogen, so it is urgent to have a corresponding method.

Patent Document 1 describes a system in which ammonia is decomposed by chlorine treatment by using sodium hypochlorite (sodium hypochlorite) obtained by electrolyzing seawater. In this system, boiler wastewater containing ammonia wastewater is introduced into a reaction tank and hypochlorous acid is added to the reaction tank, and ammonia in the boiler wastewater reacts with hypochlorous acid as a solution and is decomposed into nitrogen.

[Previous Technical Literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2014-563

[Non-patent literature]

[Non-Patent Document 1] "Efforts to remove hydrazine in water treatment in thermal power plants", [online], Mitsubishi Heavy Industries Technical Report Vol. 46 No. 2 (2009), [Search on March 30, 2012] Network <URL: http://www.mhi.co.jp/technology/review/pdf/462/462055.pdf>

Further, in the system described in Patent Document 1, the treatment liquid which has been treated in the reaction tank is discharged after the hypochlorous acid concentration and the pH in the treatment liquid are lowered to the drainage standard. The above system, for example, uses sodium thiosulfate to neutralize soda hypochlorite or alkaline soda (hydrogen peroxide) Sodium) adjusts the pH.

However, in order to treat a treatment liquid as a medicine, it is necessary to have a large pharmaceutical cost, and it is therefore desired to have a hypochlorous acid supply device that treats ammonia contained in boiler wastewater at a lower cost.

An object of the present invention is to provide a hypochlorous acid supply device and a method for treating boiler wastewater, which can treat ammonia contained in boiler wastewater at a lower cost.

According to a first aspect of the present invention, a hypochlorous acid supply device includes: a storage tank for storing seawater; and electrolyzing the seawater taken from the storage tank to generate a hypochlorous acid-containing liquid and returning it to the storage tank. An electrolysis device; and a supply line for introducing the hypochlorous acid-containing liquid stored in the storage tank; and a reaction tank for reacting the hypochlorite-containing liquid supplied from the supply line with ammonia-containing boiler wastewater; and An injection line in which a mixed liquid of the treated liquid reacted in the reaction tank and the hypochlorous acid-containing liquid stored in the storage tank is injected into a hypochlorous acid utilization facility is mixed.

According to this configuration, it is not necessary to discharge the treatment liquid stored in the reaction tank to the apparatus using hypochlorous acid, and therefore it is not necessary to perform the treatment of the medicine for satisfying the wastewater standard for treating the liquid, and the treatment cost of ammonia can be reduced.

The hypochlorous acid supply device includes: discharging the first injection line containing the hypochlorous acid liquid stored in the storage tank; and discharging a second injection line of the treatment liquid stored in the reaction tank, and the injection line is connected to the first injection line and the second injection line.

The hypochlorous acid supply device includes: a first injection line for discharging the hypochlorous acid-containing liquid stored in the storage tank; and a second injection line for discharging the processing liquid stored in the reaction tank, and the second The injection line is connected to the above storage tank.

The hypochlorous acid supply device includes a control device, and the control device adjusts a flow rate of the hypochlorous acid-containing liquid supplied to the reaction tank and a flow rate of the ammonia-containing boiler wastewater supplied to the reaction tank to The extent to which ammonia remains in the treatment liquid described above.

According to this configuration, it is possible to suppress the reaction of hypochlorous acid with the original organic matter of the seawater in the storage tank to produce trihalomethane. That is, ammonia is preferentially oxidized by hypochlorous acid, so that organic matter is difficult to oxidize, and generation of trihalomethane can be suppressed.

The hypochlorous acid supply device includes a discharge line for discharging a part of the treatment liquid flowing through the second injection line, and an activated carbon treatment unit provided on the discharge line.

According to this configuration, the unreacted or remaining hypochlorous acid (residual chlorine) is subjected to a reduction treatment to adsorb and remove nitrate ions and trihalomethanes (produced by reaction of organic substances in seawater with hypochlorous acid).

According to a second aspect of the present invention, a method for treating boiler wastewater, comprising: electrolyzing seawater and generating an electrolysis step containing a hypochlorous acid liquid; and reacting the hypochlorite-containing liquid with an ammonia-containing boiler wastewater to produce a treatment liquid. a reaction step; and mixing the treated liquid with the above-mentioned The mixed liquid of the chloric acid liquid is injected into the injection step of the hypochlorous acid utilization equipment.

According to the present invention, it is not necessary to inject the treatment liquid stored in the reaction tank into the hypochlorous acid utilization equipment, so that it is not necessary to perform the chemical treatment for satisfying the drainage standard of the treatment liquid, and the treatment cost of ammonia can be reduced.

1, 1B‧‧‧ hypochlorous acid supply device

2‧‧‧Seawater Electrolyzer

3‧‧‧ water intake (hypochlorous acid utilization equipment)

4‧‧‧First seawater supply pipeline

5‧‧‧ storage tank

6‧‧‧Drainage trough

7‧‧‧Reaction tank

8‧‧‧Drainage pipeline

9‧‧‧Drainage supply pump

10‧‧‧pH measuring device

11‧‧‧Second seawater supply pipeline

12‧‧‧Seawater supply pump

14‧‧‧electrolyzer

15‧‧‧DC power supply unit

16‧‧‧Circular pipeline

17‧‧‧Supply pipeline

18‧‧ ‧ Confluence Department

19‧‧‧ Static mixer

21‧‧‧First injection line

22‧‧‧Second injection line

23‧‧‧First flow adjustment valve

24‧‧‧Second flow adjustment valve

25‧‧‧Ammonia concentration measuring device

26‧‧‧Control device

27‧‧‧Drainage line

28‧‧‧Active carbon equipment

29‧‧‧Flow adjustment valve

B‧‧‧Exhaust heat recovery boiler

E‧‧‧ hypochlorous acid-containing liquid

M‧‧‧Seawater

P‧‧‧Factory

T‧‧‧Processing liquid

W‧‧‧Boiler wastewater

Fig. 1 is a schematic structural view showing a combined cycle power plant having a hypochlorous acid supply device according to a first embodiment of the present invention.

Fig. 2 is a schematic structural view showing a combined cycle power plant having a hypochlorous acid supply device according to a second embodiment of the present invention.

Fig. 3 is a schematic structural view showing a combined cycle power plant having a hypochlorous acid supply device according to a third embodiment of the present invention.

(First embodiment)

Hereinafter, the hypochlorous acid supply device 1 and the method for treating boiler wastewater according to the first embodiment of the present invention will be described in detail with reference to the drawings.

Fig. 1 is a schematic structural view showing a combined cycle power plant P having a hypochlorous acid supply device 1 according to a first embodiment of the present invention. Hypochlorous acid of this embodiment The supply device 1 is a hypochlorous acid utilization device that contains a liquid according to the hypochlorite soda (sodium hypochlorite) generated by the seawater electrolysis device 2, for example, to the water intake port 3 of the seawater, and also processes the combined cycle power plant. The heat-recovery boiler B discharges the ammonia-containing wastewater (ammonia-containing boiler wastewater, hereinafter referred to as boiler wastewater).

As shown in Fig. 1, the hypochlorous acid supply device 1 includes: a storage tank 5 for storing seawater M; and a seawater electrolysis device 2 for generating a liquid E containing hypochlorite soda (hereinafter referred to as hypochlorous acid-containing liquid E); a drain tank 6 for storing boiler waste water W discharged from a heat recovery boiler B (hereinafter referred to as boiler B) of a combined cycle power plant P (hereinafter referred to as plant P); and a reaction tank provided on the downstream side of the drain tank 6 7; and a supply line 17 for supplying the hypochlorous acid-containing liquid E to the reaction tank 7.

Plant P has: a gas turbine generator (not shown); and a boiler that delivers exhaust gas from the gas turbine generator; and a steam turbine engine (not shown); and a gas turbine generator and a steam turbine engine The generator that drives and generates electricity by the rotational driving force (not shown).

The seawater M taken out from the water intake port 3 of the seawater through the first seawater supply line 4 is introduced into the plant P, and is used, for example, for cooling or the like. The first seawater supply line 4 is provided with a seawater supply pump (not shown) that transports the seawater M, and a seawater flow rate adjustment valve (not shown) that adjusts the flow rate of the seawater M.

In the boiler waste water W of the boiler, ammonia is used as an oxygen scavenger to remove oxygen which is the main cause of corrosion. Therefore, the boiler wastewater W discharged from the boiler is ammonia-containing nitrogen wastewater (ammonia-containing boiler wastewater) containing ammonia nitrogen such as ammonia (NH ₃ ) or ammonium ions (NH ₄ ⁺ ).

The boiler wastewater W discharged from the boiler B is stored in the drain tank 6. A reaction tank 7 is provided on the downstream side of the drain tank 6. The drain tank 6 and the reaction tank 7 are connected together via a drain line 8. The boiler wastewater W stored in the drain tank 6 is introduced into the reaction tank 7 through the drain line 8. On the drain line 8, a waste water supply pump 9 for conveying the boiler waste water W stored in the drain tank 6 to the reaction tank 7 is provided.

The storage tank 5 is a tank for storing the seawater M and the hypochlorous acid-containing liquid E generated in the seawater electrolysis device 2. In the storage tank 5, the seawater M is introduced from the water intake port 3 via the second seawater supply line 11. The second seawater supply line 11 is provided with a seawater supply pump 12 that transports the seawater M, and a seawater flow rate adjustment valve (not shown) that adjusts the flow rate of the seawater M.

The seawater electrolysis device 2 generates a hypochlorous acid-containing liquid E containing hypochlorite soda by electrolysis of seawater M taken from the storage tank 5 and returns it to the storage tank 5. The seawater electrolysis device 2 has an electrolysis cell 14 and a DC power supply device 15 and a circulation line 16 for circulating the hypochlorous acid-containing liquid E. The electrolytic cell 14 has a plurality of electrodes (not shown).

The DC power supply device 15 is a device that supplies a current for electrolyzing the seawater M. For example, a configuration including a DC power supply and a constant current control circuit can be employed. The DC power source is a power source that outputs DC power. For example, the AC power output from the AC power source can be rectified to DC and output.

In the seawater electrolysis device 2 of the present embodiment, the downstream side of the electrolytic cell 14 (the outlet of the electrolytic cell 14) and the upstream of the electrolytic cell 14 are provided. The side (the inlet of the electrolytic cell 14) is connected via a circulation line 16 to recycle the seawater M. As the seawater electrolysis device 2, in addition to the above-described recovery method, a direct current method in which only seawater is passed to the electrolytic cell once may be employed. That is, the seawater electrolysis device 2 can be in any form as long as it can use seawater to produce hypochlorous acid.

A supply line 17 for supplying the hypochlorous acid-containing liquid E stored in the storage tank 5 to the drain line 8 is connected to the storage tank 5. A first injection line 21 for injecting the hypochlorous acid-containing liquid E stored in the storage tank 5 into the water intake port 3 of the hypochlorous acid utilization equipment is connected to the storage tank 5. By injecting the hypochlorite-containing liquid E into the water intake port 3, it is possible to suppress the attachment of marine organisms to the water intake port 3.

On the drain line 8, a static agitator 19 that promotes mixing of the boiler wastewater W with the hypochlorous acid-containing liquid E is provided on the downstream side (the reaction tank 7 side) from the junction portion 18 of the supply line 17.

In the reaction tank 7 of the present embodiment, a second injection line 22 for introducing the treated liquid T which has reacted in the reaction tank 7 to the first injection line 21 is connected. The treatment liquid T of the reaction tank 7 is injected into the water intake port 3 through the second injection line 22 and the first injection line 21. The first injection line 21 and the second injection line 22 function as: injecting the mixed liquid which has been mixed with the treated liquid T in the reaction tank 7 and the hypochlorous acid liquid E stored in the storage tank 5 The injection line of the water intake 3.

Next, the function of the hypochlorous acid supply device 1 of the present embodiment will be described.

First, the factory cooling step is to supply seawater M through the first seawater. The line 4 is supplied to the factory P. The boiler waste water W discharged from the boiler B of the plant P is stored in the drain tank 6. The boiler wastewater W stored in the drain tank 6 is introduced into the reaction tank 7 through the drain line 8.

On the other hand, in the electrolysis step, the seawater M is introduced into the storage tank 5 through the second seawater supply line 11, and the hypochlorous acid-containing liquid E is produced by the seawater electrolysis device 2. The hypochlorous acid-containing liquid E is introduced into the reaction tank 7 via the supply line 17. The hypochlorite-containing liquid E is also injected into the water intake port 3 through the first injection line 21.

Further, the flow rate of the hypochlorite-containing liquid E to be injected is adjusted by a control device (not shown) to control a flow rate adjusting valve (not shown) provided in the first injection line 21. In the control device, the flow rate of the hypochlorite-containing liquid E is adjusted in such a manner that hypochlorous acid is almost consumed in the water intake port 3 and returned to the original seawater M.

Next, in the reaction step, ammonia present in the boiler wastewater W in the reaction tank 7 is reacted with hypochlorous acid contained in the hypochlorous acid-containing liquid E as a solution and decomposed into nitrogen gas (N ₂ ). In the reaction tank 7, ammonia is treated and the treatment liquid T is stored in the reaction tank 7.

At this time, there is a case where hypochlorous acid used for decomposition of ammonia remains in the treatment liquid T. When the pH of the liquid T (hydrogen ion concentration index) is processed, there is also a case where the drainage standard is reached. Therefore, if the treatment liquid T is not treated as a medicine, the treatment liquid T cannot be discharged to the sea, for example.

Next, the injection step is to introduce the treatment liquid T stored in the reaction tank 7 into the first injection line 21 and mix it with the hypochlorous acid-containing liquid E. Hehe. The treatment liquid T in the reaction tank 7 is introduced into the first injection line 21 via the second injection line 22.

The mixed liquid of the treatment liquid T in the mixing reaction tank 7 and the hypochlorous acid liquid E in the storage tank 5 is injected into the water intake port 3. The boiler wastewater W treated with ammonia in the reaction tank 7 is injected into the water intake port 3 without being discharged.

According to the above embodiment, by adding the hypochlorous acid-containing liquid E containing hypochlorous acid to the boiler wastewater W containing the ammonia nitrogen-containing wastewater, the ammonia contained in the boiler wastewater W can be decomposed and treated.

Further, since the treatment liquid T stored in the reaction tank 7 is not required to be discharged but is injected into the water intake port 3 of the hypochlorous acid utilization equipment, it is not necessary to perform the treatment of the medicine in order to satisfy the drainage standard of the treatment liquid T, and the ammonia can be reduced. Processing costs.

Further, the hypochlorous acid-containing liquid E generated in the seawater electrolysis device 2 is injected into the water intake port 3 of the seawater M through the first injection line 21. By injecting the hypochlorite-containing liquid E into the water intake port 3, it is possible to suppress the attachment of marine organisms to the water intake port 3.

(Second embodiment)

Hereinafter, a hypochlorous acid supply device 1B according to a second embodiment of the present invention will be described with reference to the drawings. In the present embodiment, differences from the above-described first embodiment will be mainly described, and the same portions will not be described.

As shown in Fig. 2, the second injection line 22 of the hypochlorous acid supply device 1B of the present embodiment is connected to the storage tank 5. The treatment liquid T in the reaction tank 7 is introduced into the storage tank 5.

The drain line 8 of the present embodiment is provided with a first flow rate adjusting valve 23 for regulating the flow rate of the boiler wastewater W flowing through the drain line 8. Further, the supply line 17 of the present embodiment is provided with a second flow rate adjusting valve 24 for adjusting the flow rate of the hypochlorous acid-containing liquid E flowing through the supply line 17.

In the reaction tank 7 of the hypochlorous acid supply device 1 of the present embodiment, an ammonia concentration measuring device 25 that measures the ammonia concentration of the treatment liquid T stored in the reaction tank 7 is provided.

Next, the function of the hypochlorous acid supply device 1B of the present embodiment will be described.

The control device 26 adjusts the flow rate of the boiler wastewater W introduced into the reaction tank 7 and the flow rate of the hypochlorous acid-containing liquid E by controlling the first flow rate adjusting valve 23 and the second flow rate adjusting valve 24. The control device 26 adjusts the flow rate of the boiler waste water and the flow rate of the hypochlorous acid-containing liquid E to the extent that ammonia remains in the treatment liquid T stored in the reaction tank 7. In the hypochlorous acid supply device 1 of the present embodiment, the ammonia in the boiler wastewater W in the reaction tank 7 is not completely decomposed, but remains in the treatment liquid T.

Further, as long as ammonia can remain in the treatment liquid T, it is not necessary to adjust both the hypochlorite-containing liquid E and the boiler wastewater W, and it is only necessary to adjust the flow rate at either side to make the residual ammonia in the treatment liquid T.

Specifically, the control device 26 adjusts at least one of the hypochlorous acid-containing liquid E and the boiler wastewater W so that ammonia remains in the treatment liquid T.

The injection step is: the ammonia-containing treatment liquid T is given a second injection The inlet line 22 is introduced into the storage tank 5. That is, the liquid T is not discharged, but is returned to the storage tank 5. Thereby, ammonia is added to the seawater M and the hypochlorous acid-containing liquid E stored in the storage tank 5.

According to the above embodiment, the storage tank 5 can suppress the reaction of hypochlorous acid with the organic matter derived from the seawater M to produce trihalomethane. That is, the ammonia introduced into the storage tank 5 at the same time as the treatment liquid T is preferentially oxidized by hypochlorous acid, so that the organic substance is hard to be oxidized. Therefore, the production of trihalomethane can be suppressed.

(Third embodiment)

Hereinafter, a hypochlorous acid supply device 1C according to a third embodiment of the present invention will be described with reference to the drawings. In the present embodiment, differences from the above-described first embodiment will be mainly described, and the same portions will not be described.

As shown in Fig. 3, the second injection line 22 of the hypochlorous acid supply device 1C of the present embodiment is connected to a discharge line 27 for discharging a part of the treatment liquid T flowing through the second injection line 22. A portion of the process liquid T flowing through the second injection line 22 is discharged through the discharge line 27.

On the discharge line 27, an activated carbon treatment unit 28 is provided. The activated carbon treatment device 28 is a device that passes the treatment liquid T through activated carbon to perform activated carbon treatment.

Further, the discharge line 27 is provided with a flow rate adjusting valve 29 for adjusting the flow rate of the treatment liquid T flowing through the discharge line 27.

In the activated carbon treatment apparatus 28, the remaining residual chlorine is decomposed according to the decomposition reaction represented by the formula (1). Here, the activity of NaClO per 1 kg The carbon usage is about 0.08 kg.

2NaClO+C→CO ₂ +2NaCl. . . (1)

On the other hand, according to the reaction using a chemical such as sodium thiosulfate (Na ₂ SO ₃ ) represented by the formula (2), when the remaining residual chlorine is decomposed, the amount of sodium thiosulfate per 1 kg of NaClO is about 1.7 kg.

NaClO+Na ₂ SO ₃ →NaCl+Na ₂ SO ₄ . . . (2)

According to the above embodiment, by providing the activated carbon treatment device 28 on the discharge line 27, the unreacted or remaining hypochlorous acid (residual chlorine) is subjected to a reductive treatment to adsorb and remove nitrate ions and trihalomethanes (organic matter in seawater). Produced by hypochlorous acid reaction).

Further, the treatment liquid T discharged from the reaction tank 7 is treated to a state in which it can be discharged. Therefore, in the case where the chloride ion concentration of seawater is low, the treated water T which is mixed with the boiler wastewater and is diluted flows into the water intake port 3, and when the chlorine ion concentration becomes lower, the activated carbon treatment equipment is used. The treated water T is discharged to the outside, and the decrease in the concentration of chlorine ions can be suppressed.

The flow rate of the treatment liquid T discharged from the discharge line 27 can be adjusted using the flow rate adjustment valve 29.

Further, in the case where a part of the treatment liquid T is discharged, the amount of the medicine used can be reduced as compared with the case of decomposition using sodium thiosulfate. Furthermore, it is not necessary to control the amount of the drug required for the decomposition using sodium thiosulfate.

In addition, the technical scope of the present invention is not limited to the above embodiments, and various changes can be added without departing from the scope of the invention.

For example, the supply line 17 containing the hypochlorous acid liquid E of each of the above embodiments is the drain line 8 connected to the boiler waste water W. However, the supply line 17 may be directly connected to the reaction tank 7.

Further, the supply line 17 and the first injection line 21 of the above-described respective embodiments are connected to the storage tank 5, respectively, but the first injection line 21 may be branched from the supply line 17.

Further, the discharge line 27 of the third embodiment may be provided in the hypochlorous acid supply device 1B of the second embodiment.

1‧‧‧ hypochlorous acid supply unit

2‧‧‧Seawater Electrolyzer

3‧‧‧ water intake (hypochlorous acid utilization equipment)

4‧‧‧First seawater supply pipeline

5‧‧‧ storage tank

6‧‧‧Drainage trough

7‧‧‧Reaction tank

8‧‧‧Drainage pipeline

9‧‧‧Drainage supply pump

11‧‧‧Second seawater supply pipeline

12‧‧‧Seawater supply pump

14‧‧‧electrolyzer

15‧‧‧DC power supply unit

16‧‧‧Circular pipeline

17‧‧‧Supply pipeline

18‧‧ ‧ Confluence Department

19‧‧‧ Static mixer

21‧‧‧First injection line

22‧‧‧Second injection line

B‧‧‧Exhaust heat recovery boiler

E‧‧‧ hypochlorous acid-containing liquid

M‧‧‧Seawater

P‧‧‧Factory

T‧‧‧Processing liquid

W‧‧‧Boiler wastewater

Claims (6)

A hypochlorous acid supply device characterized by: a storage tank for storing seawater; and an electrolysis device for electrolyzing the seawater taken from the storage tank to produce a hypochlorous acid-containing liquid and returning it to the storage tank; and introducing and storing a supply line containing the hypochlorous acid liquid in the storage tank; and a reaction tank for reacting the hypochlorite-containing liquid supplied from the supply line with the ammonia-containing boiler wastewater; and mixing the reaction The mixed reaction liquid of the reaction liquid in the tank and the above hypochlorous acid liquid stored in the storage tank is injected into an injection line of the hypochlorous acid utilization equipment. The hypochlorous acid supply device according to claim 1, comprising: a first injection line for discharging the hypochlorous acid-containing liquid stored in the storage tank; and a second discharge of the treatment liquid stored in the reaction tank The injection line is formed by connecting the first injection line and the second injection line. The hypochlorous acid supply device according to claim 1, wherein: the first injection line for discharging the hypochlorous acid-containing liquid stored in the storage tank; and The second injection line of the treatment liquid stored in the reaction tank is discharged, and the second injection line is connected to the storage tank. The hypochlorous acid supply device according to claim 3, further comprising: a control device, wherein the control device supplies a flow rate of the hypochlorous acid-containing liquid supplied to the reaction tank and the ammonia-containing boiler supplied to the reaction tank The flow rate of the wastewater is adjusted to the extent that ammonia remains in the above treatment liquid. The hypochlorous acid supply device according to claim 2, 3 or 4, further comprising: a discharge line for discharging a part of the treatment liquid flowing through the second injection line; and activated carbon provided on the discharge line Processing device. A method for treating boiler wastewater, characterized by having: an electrolysis step of electrolyzing seawater to produce a hypochlorous acid-containing liquid; and a reaction step of reacting the hypochlorous acid-containing liquid with ammonia-containing boiler wastewater to produce a treatment liquid; An injection step of injecting a mixed liquid of the treatment liquid and the above hypochlorous acid-containing liquid into the hypochlorous acid utilization apparatus.