WO2021176682A1

WO2021176682A1 - Water discharging method, water treating method, residual chlorine reduction method, and water treatment facility

Info

Publication number: WO2021176682A1
Application number: PCT/JP2020/009633
Authority: WO
Inventors: 司吉崎; 一郎内山; 直彦谷口; 柳川　敏治; 圭二尾山; 中村　明博
Original assignee: 中国電力株式会社
Priority date: 2020-03-06
Filing date: 2020-03-06
Publication date: 2021-09-10
Also published as: WO2021176774A1

Abstract

The present invention reduces the residual chlorine concentration of water released to a natural water area such as an ocean.　A water treating method for taking water from a natural water area into a waterway through an intake port 21 and discharging the water, which had been taken into the waterway 25, to the natural water area through a discharge port 24, the method comprising a step for adding, to the water, a chlorine-based chemical agent at a predetermined position in the waterway 25, and a step for adding, to the water, hydrogen gas or a hydrogen-containing liquid that contains dissolved hydrogen at a position on the side of the discharge port 24 with respect to said predetermined position.

Description

Water discharge method, water treatment method, residual chlorine reduction method and water treatment equipment

The present invention relates to a water discharge method, a water treatment method, a residual chlorine reduction method, and a water treatment facility.

Intake channels and drainage channels are laid from the sea area to the inside of the power plant in order to take in seawater for water cooling of equipment such as condensers in the power plant and to discharge the taken in seawater. Marine organisms such as wisteria and mussels breed inside the intake and drainage channels, and such attachment of marine organisms causes narrowing or blockage of the intake and drainage channels and the condenser cooling pipe. As a result, the flow rate of the intake water and the discharged water is lowered, and the condensate cooling efficiency is lowered. When a chlorine-based chemical is introduced into the intake channel in order to solve such a problem, the generation of marine organisms in the intake channel and the discharge channel can be suppressed. Patent Document 1 describes a method of preventing marine organisms from adhering to intake channels and drainage channels by using a chlorine-based disinfectant.

Japanese Unexamined Patent Publication No. 2019-76813

However, if the concentration of residual chlorine in the seawater released from the drainage channel to the sea is high, it will adversely affect the natural environment of the sea.

Therefore, the purpose of this disclosure is to reduce the residual chlorine concentration in water.

As a result of diligent research, the present inventors have obtained a new finding that when a hydrogen-containing liquid containing dissolved hydrogen or gaseous hydrogen is added to water containing residual chlorine, the residual chlorine contained in the water is reduced.

Therefore, in order to solve the above problems, in a water discharge method in which the water is discharged from a facility in which water containing residual chlorine is used to a natural water area through a flood bypass, a hydrogen-containing liquid containing dissolved hydrogen or gaseous hydrogen is released. Add to the water in the channel.

Further, in order to solve the above problems, in a water treatment method in which water from a natural water area is taken into a water channel through a water outlet and the water taken into the water channel is discharged to the natural water area through an outlet, a predetermined position of the water channel is used. In, a chlorine-based chemical is added to the water, and a hydrogen-containing liquid containing dissolved hydrogen or gaseous hydrogen is added to the water at a position closer to the outlet side than the predetermined position.

The seawater facility for solving the above problems is provided between the facility and the natural water area, and has a flood channel for discharging water containing residual chlorine from the facility to the natural water area, and a hydrogen-containing liquid containing dissolved hydrogen or a hydrogen-containing liquid. It is provided with an addition device for adding gaseous hydrogen to the water in the flood bypass.

Further, the seawater facility for solving the above problems has an intake port and a water discharge port provided in a natural water area, takes in water from the natural water area through the water intake port, and takes in the taken water through the water discharge port. A hydrogen-containing liquid or gaseous hydrogen containing dissolved hydrogen at a position on the outlet side of the water channel where a chlorine-based chemical is added to the water in the water channel at a predetermined position of the water channel to be discharged into the natural water area. Is provided with an addition device for adding water to the water in the water channel.

According to the present disclosure, the residual chlorine concentration in water is reduced. Therefore, for example, even when water is released into a natural water area, it does not adversely affect the environment of the natural water area.

It is a top view of a thermal power plant in which seawater equipment is constructed. It is a schematic diagram of a seawater facility and a condenser.

Hereinafter, embodiments will be described with reference to the drawings. Although various technically preferable limitations are attached to the embodiments described below, the scope of the present invention is not limited to the following embodiments and illustrated examples.

FIG. 1 is a plan view of the thermal power plant 10. FIG. 2 is a schematic view of the seawater facility 11 (corresponding to the water treatment facility of the present invention) and the condenser 18 constructed in the thermal power plant 10.

The thermal power plant 10 is constructed on a site facing the sea 2 as a natural water area. The thermal power plant 10 includes a seawater facility 11, a fuel storage facility 14, and a power generation facility 16. The seawater facility 11 has a water channel 25 and an addition device 30.

The power generation facility 16 includes a turbine, a boiler, a generator, and a condenser 18 (not shown). When the fuel supplied to the boiler from the fuel storage facility 14 is burned, high-temperature and high-pressure steam is generated in the boiler, the turbine and the generator are driven by the energy of the steam, and electric energy is generated in the generator. .. The condenser 18 as equipment is connected to the turbine, and the steam discharged from the turbine is supplied to the condenser 18. The condenser 18 is a surface condenser or a mixed condenser.

The water channel 25 of the seawater facility 11 has an intake channel 20 on the upstream side of the condenser 18 and a flood channel 22 on the downstream side of the condenser 18. The intake channel 20 is a channel for taking in the salt water of the sea 2 into the thermal power plant 10. The intake channel 20 is constructed on the ground from the sea or the seabed to the condenser 18 or its vicinity. The end of the intake channel 20 opens in the sea or on the seabed, and the opening is the intake port 21. The salt water of the sea 2 is taken into the intake channel 20 through the intake port 21. The salt water taken into the intake channel 20 is sent to the condenser 18. The flood channel 22 is a channel for discharging salt water to the sea 2. The flood bypass 22 is constructed on the ground from the sea or the seabed to the condenser 18 or its vicinity. The end of the floodway 22 opens in the sea or on the seabed, and the opening is the drainage port 24. The salt water in the condenser 18 is discharged to the drainage channel 22, and the discharged water is sent to the discharge port 24. Then, the salt water is discharged to the sea 2 through the discharge port 24.

The inlet of the condenser 18 is connected to the intake channel 20 via a flow path, a pump 19, and the like. The outlet of the condenser 18 is connected to the flood channel 22 via a flow path or the like. The pump 19 sends the salt water in the intake channel 20 to the condenser 18. The salt water supplied to the condenser 18 cools and condenses the steam supplied from the turbine. The salt water used for cooling in the condenser 18 is discharged to the flood channel 22 and discharged to the sea 2 through the flood channel 22. In addition, instead of the pump 19, the potential energy or the pressure difference may be used to allow salt water to flow from the sea 2 to the sea 2 via the intake channel 20, the condenser 18, and the drainage channel 22.

Since salt water containing marine organisms flows through the intake channel 20, the drainage channel 22, and the condenser 18, marine organisms easily adhere to and propagate inside the intake channel 20, the drainage channel 22, and the condenser 18. A chlorine-based chemical is added to the salt water in the intake channel 20 by the addition device 30 in order to suppress the adhesion and reproduction of marine organisms. Further, in order to reduce the residual chlorine concentration of the salt water discharged from the discharge channel 22 into the sea 2, water containing dissolved hydrogen (hereinafter referred to as hydrogen water) is added to the salt water in the discharge channel 22 by the addition device 30. NS. In the following description, the water used as the solvent for hydrogen water is salt water, but it may be fresh water or clean water.

The addition device 30 will be described in detail below.
The addition device 30 includes an electrolyzer 31, a gas dissolution device 41,

liquid feed pumps

35, 44, and a valve 45.

The inlet of the electrolysis device 31 is connected to the intake channel 20 via the introduction pipe 32 and the liquid feed pump 35, and the liquid outlet of the electrolysis device 31 is connected to the intake channel 20 via the discharge pipe 33. The gas outlet of 31 is connected to the gas inlet of the gas dissolving device 41 via a transmission pipe 34. The liquid inlet of the gas dissolving device 41 is connected to the intake channel 20 via the introduction pipe 42 and the liquid feeding pump 44, and the liquid outlet of the gas dissolving device 41 is connected to the drainage channel 22 via the valve 45 and the discharge pipe 43. Has been done.

The liquid feed pump 35 supplies the salt water in the intake channel 20 to the electrolyzer 31.
_{The electrolyzer 31 generates chlorine (Cl 2} ) at the anode of the electrolyzer 31 by electrolyzing the salt water introduced from the intake channel 20. Therefore, the salt water electrolyzed by the electrolyzer 31 contains effective chlorine composed of free chlorine, combined chlorine, and the like. The free chlorine, chlorine gas molecules (Cl ₂₎ in the brine, hypochlorous acid (HClO) and hypochlorous acid ions (ClO ^-) refers to. Bound chlorine is obtained by reacting free chlorine with ammonia contained in salt water and its compound, and refers to chloramines such as monochloramine, dichloramine, and trichloramine.

_{Hydrogen (H 2} ) is generated at the cathode of the electrolyzer 31 by the electrolysis of salt water in the electrolyzer 31. The electrolysis device 31 has a degassing tower or a receiving tank or the like, and hydrogen molecules in the electrolyzed salt water are separated from the salt water in the degassing tower or the receiving tank or the like, and gaseous hydrogen is generated from the salt water. The gaseous hydrogen is sent from the electrolyzer 31 to the gas dissolving apparatus 41 through the transmission pipe 34. A valve for adjusting the flow rate of gaseous hydrogen from the electrolyzer 31 to the gas dissolution device 41 may be provided in the middle of the transmission pipe 34.

The salt water from which hydrogen is separated in the electrolyzer 31 is a chlorine-based chemical, and more specifically, it is a chlorine-based aqueous solution containing effective chlorine. The chlorine-based aqueous solution is introduced into the intake channel 20 from the electrolyzer 31 through the discharge pipe 33. Since the chlorine-based aqueous solution is added to the salt water in the intake channel 20, the adhesion and reproduction of marine organisms are suppressed. The position where the chlorine-based aqueous solution is added from the discharge pipe 33 to the intake channel 20 is as close as possible to the intake port 21 in order to obtain the effect of preventing the adhesion and reproduction of marine organisms in the widest possible range of the intake channel 20. Is preferable.

In the example shown in FIG. 2, one liquid feeding pump 35 is provided. On the other hand, a plurality of liquid feeding pumps 35 may be provided in the path from the intake passage 20 to the intake pipe 20 via the introduction pipe 32, the electrolyzer 31 and the discharge pipe 33. Further, one or more valves may be provided in the path from the intake pipe 20 to the intake pipe 20 via the introduction pipe 32, the electrolyzer 31 and the discharge pipe 33. One or more liquid feed pumps 35 and valves adjust the supply flow rate of salt water from the intake channel 20 to the electrolyzer 31 and adjust the input flow rate of the chlorine-based aqueous solution from the electrolyzer 31 to the intake channel 20. Or By controlling the liquid feed pump 35 and the valve, and controlling the power consumption of the electrolyzer 31, the residual chlorine concentration in the intake channel 20 and the condenser 18 and the discharge channel 22 on the downstream side thereof is appropriate. Is adjusted to.

The liquid feed pump 44 supplies the salt water in the intake channel 20 to the gas dissolving device 41. The liquid inlet of the gas dissolving device 41 is connected to the drainage channel 22 via the introduction pipe 42 and the liquid feeding pump 44, and the liquid feeding pump 44 supplies the salt water in the drainage channel 22 to the gas dissolving device 41. May be good.

The gas melting device 41 dissolves the gaseous hydrogen introduced from the electrolyzer 31 in the salt water introduced from the intake channel 20. As a result, salt water containing dissolved hydrogen (hereinafter referred to as hydrogen water) is generated in the gas dissolving device 41. In the gas dissolution device 41, the gas hydrogen is efficiently dissolved in salt water and the concentration of dissolved hydrogen in the hydrogen water is increased. Therefore, the inside of the gas dissolution device 41 may be pressurized to a high pressure by a compressor or the like.

The hydrogen water generated in the gas dissolving device 41 is introduced from the gas dissolving device 41 into the flood channel 22 through the valve 45 and the discharge pipe 43. The valve 45 adjusts the flow rate of hydrogen water input to the drainage channel 22. By adding hydrogen water to the salt water in the drainage channel 22, residual chlorine in the salt water is reduced or removed, and the salt water is neutralized. The neutralized salt water is discharged from the flood channel 22 into the sea 2. The residual chlorine concentration of the neutralized salt water does not affect the natural environment of the sea 2, and is, for example, less than or equal to the value stipulated by the agreement with the local community, laws, regulations, and the like. In order to widen the region of the discharge channel 22 where the residual chlorine concentration of the salt water is high, the position where hydrogen water is added from the discharge pipe 43 is better as it is closer to the discharge port 24. In particular, if the residual chlorine concentration of the salt water released into the sea 2 can be suppressed to be equal to or lower than the predetermined value, it is preferable that the hydrogen water is added from the discharge pipe 43 to the vicinity of the discharge port 24.

According to the above embodiment, the following advantageous effects are brought about.

(1) Since the hydrogen water generated by the gas dissolving device 41 is put into the salt water in the drainage channel 22, the residual chlorine concentration of the saltwater discharged from the drainage channel 22 into the sea 2 is reduced. Therefore, it does not adversely affect the natural environment in the sea 2.

(2) Since the chlorine-based aqueous solution generated by the electrolyzer 31 is put into the salt water in the intake channel 20, the adhesion and reproduction of marine organisms in the intake channel 20, the condenser 18, and the drainage channel 22 are suppressed. .. In particular, since the residual chlorine concentration of the salt water in the flood channel 22 is reduced, it is not necessary to lower the effective chlorine concentration of the chlorine-based aqueous solution generated by the electrolyzer 31, and the adhesion and reproduction of marine organisms are ensured. It can be suppressed.

(3) Since the gaseous hydrogen generated from the salt water is used in the electrolyzer 31, it is not necessary to separately prepare hydrogen in order to reduce the residual chlorine in the salt water. The residual chlorine concentration of salt water in the drainage channel 22 can be reduced at low cost. Further, it is not necessary to release gaseous hydrogen to the atmosphere in the electrolyzer 31.

(4) The gaseous hydrogen generated in the electrolyzer 31 is not directly injected into the salt water in the drainage channel 22, but the gaseous hydrogen is once dissolved in the salt water by the gas dissolving apparatus 41, and then the hydrogen water is discharged. It is added to the salt water in the discharge channel 22. Therefore, the neutralization of salt water in the drainage channel 22 proceeds efficiently.

The embodiment has been described above. The above embodiments may be modified or improved. The changes from the above embodiments will be described below. Each of the changes described below may be applied in combination.

(A) In the above embodiment, the chlorine-based chemical added to the salt water in the intake channel 20 is a chlorine-based aqueous solution generated by the electrolyzer 31. On the other hand, a chlorine-based aqueous solution that has been generated in advance and stored in a storage tank or the like may be added to the salt water in the intake channel 20 by the charging device. The chlorine-based aqueous solution is, for example, a hypochlorous acid aqueous solution or a chlorinated isocyanuric acid aqueous solution, but other chlorine-based aqueous solutions may be used. Further, instead of the chlorine-based aqueous solution, chlorine gas may be ejected into the salt water in the intake channel 20. Chlorine gas is stored in a gas cylinder. Further, instead of the chlorine-based aqueous solution, a solid chlorine-based chemical may be charged into the salt water in the intake channel 20 by the charging device. The solid chlorine-based chemicals are, for example, calcium hypochlorite, sodium hypochlorite, chlorinated isocyanuric acid or bleached powder. The solid chlorine-based chemicals are stored in the storage tank in advance.

(B) In the above embodiment, the gaseous hydrogen generated by the electrolyzer 31 is supplied to the gas dissolution apparatus 41. On the other hand, the addition device 30 may have a gas cylinder or a hydrogen generating device, and the gaseous hydrogen stored in the gas cylinder or the gaseous hydrogen generated by the hydrogen generating apparatus may be supplied to the gas melting device 41. The hydrogen generator is, for example, an electrolyzer that electrolyzes water to generate hydrogen and oxygen.

(C) In the above embodiment or the above modified example (B), gaseous hydrogen is previously dissolved in salt water in the gas dissolving apparatus 41. On the other hand, the gaseous hydrogen may be directly ejected into the salt water in the drainage channel 22, and the gaseous hydrogen may be dissolved in the salt water.

(D) In the above embodiment, the salt water in the intake channel 20 or the discharge channel 22 is supplied to the gas dissolving device 41. On the other hand, clean water may be supplied to the gas dissolving device 41. Further, fresh water in a natural water area other than the sea 2 may be supplied to the gas dissolving device 41.

(E) In the above embodiment, the natural water area is the sea 2, and the thermal power plant 10 is built on the coast of the sea 2. On the other hand, the natural water area may be a salt lake, a freshwater lake, a swamp or a river, and the thermal power plant 10 may be constructed on the coast of the salt lake, a freshwater lake, a swamp or a river. When the water existing in the natural water area is fresh water, it is necessary to apply the modified examples of (A) and (B) together, or to dissolve sodium chloride in the fresh water supplied to the electrolyzer 31. There is a need. Since brackish water is salt water, the brackish lake is a kind of salt lake in this disclosure.

(F) In the above embodiment, the seawater facility 11 is constructed in the thermal power plant 10. On the other hand, the seawater facility 11 may be constructed in another type of power plant, for example, a hydroelectric power plant, a pumped storage power plant, or a nuclear power plant, or may be constructed in a factory other than the power plant. .. Further, although the equipment provided between the intake channel 20 and the drainage channel 22 was the condenser 18, other equipment, for example, a hydroelectric generator may be used.

(G) The position where hydrogen water or gaseous hydrogen is added may be any position from the position where the chlorine-based aqueous solution is added to the intake pipe 20 from the discharge pipe 33 to the outlet 24. However, in order to prevent marine organisms from adhering to the condenser 18, it is preferable that the position where hydrogen water or gaseous hydrogen is added is on the downstream side of the condenser 18.

It was verified by five tests (one of which was a comparative test) that the residual chlorine concentration was reduced by mixing hydrogen water with water containing residual chlorine (hereinafter referred to as chlorine water). This will be described in detail below.

A hypochlorous acid solution was used as the chlorinated water.
As hydrogen water, hydrogen gas was introduced into pure water in a beaker from a hydrogen tank and stirred while bubbling. No catalyst such as platinum is used. When the hydrogen concentration of the hydrogen water thus obtained was measured with a hydrogen concentration meter, it was about 0.8 ppm.

Equal amounts of the above chlorine water and hydrogen water (50 ml each in this test) were mixed in a beaker, and the mixed water was stirred to determine the residual chlorine concentration. The residual chlorine concentration was measured by the DPD method. At the same time, the hydrogen concentration after mixing was also measured with a hydrogen concentration meter. When mixing and stirring chlorine water and hydrogen water, other means such as ultraviolet irradiation are not used.

Tables 1 to 4 show the chlorine concentration of chlorine water before mixing, the residual chlorine concentration at the time of mixing, and immediately after mixing, 5 minutes after mixing, and 10 in each of the four tests in which chlorine water and hydrogen water were mixed. The residual chlorine concentration and hydrogen concentration after 1 minute and 15 minutes, and the reduced concentration immediately after mixing are shown. The residual chlorine concentration and hydrogen concentration at the time of mixing are half of the residual chlorine concentration and hydrogen concentration before mixing, but this was diluted to 50% by mixing equal amounts of chlorine water and hydrogen water. It depends.
In addition, Table 5 shows the results when 50 ml each of chlorinated water and pure water are mixed as a comparative example.
As shown in Table 5, in the case of the comparative example, no decrease in the residual chlorine concentration was observed even after mixing, whereas as shown in Tables 1 to 4, hydrogen water was mixed with chlorine water. In all the tests, the residual chlorine concentration decreased with the passage of time, and a decrease of 0.06 to 0.12 ppm was observed 15 minutes after mixing.

As described above, it was confirmed that the residual chlorine concentration can be reduced by mixing hydrogen water with chlorine water.

The test results are shown in Tables 1 to 5 below.

In the above test, it was confirmed that the chlorine concentration decreased by mixing hydrogen water with chlorine water, but as described above, the hydrogen water used in the test was obtained by bubbling hydrogen gas into pure water. Therefore, the same effect can be expected by bubbling hydrogen gas directly into chlorine water.

2 ... Sea (natural water area)
18 ... Condenser (equipment)
20 ... Intake channel 22 ... Flood channel 25 ... Water channel 30 ... Addition device 31 ... Electrolysis device 41 ... Gas dissolution device

Claims

In a water discharge method in which water containing residual chlorine is discharged from a facility in which water is used to a natural water area through a flood channel.
A water discharge method comprising adding a hydrogen-containing liquid containing dissolved hydrogen or gaseous hydrogen to the water in the flood bypass.
The water discharge method according to claim 1, wherein gaseous hydrogen is generated by electrolysis of water, and the gaseous hydrogen is dissolved in a liquid to obtain the hydrogen-containing liquid.
In a water treatment method in which water from a natural water area is taken into a waterway through a water outlet and the water taken into the waterway is discharged to the natural water area through an outlet.
Water characterized in that a chlorine-based chemical is added to the water at a predetermined position in the water channel, and a hydrogen-containing liquid containing dissolved hydrogen or gaseous hydrogen is added to the water at a position closer to the outlet side than the predetermined position. Processing method.
The water channel is provided between the intake port and the equipment, and is provided between the intake channel for sending the water taken in from the intake port to the equipment and the equipment and the water discharge port, and the water is supplied to the equipment. It has a drainage channel that sends from to the outlet.
The water treatment method according to claim 3, wherein the predetermined position for adding the chlorine-based chemical is in the intake channel, and the position for adding the hydrogen-containing liquid or the gaseous hydrogen is in the drainage channel.
The natural water area is the sea or a salt lake, and the water taken in through the intake is salt water.
The salt water is supplied from the water channel to the electrolyzer, the salt water is electrolyzed by the electrolyzer to generate gaseous hydrogen, and the gaseous hydrogen is dissolved in a liquid by the gas dissolving apparatus to dissolve the hydrogen-containing liquid. The water treatment method according to claim 3 or 4.
A method for reducing residual chlorine by adding a hydrogen-containing liquid containing dissolved hydrogen or gaseous hydrogen to water containing residual chlorine.
A flood bypass provided between the equipment and the natural water area to discharge water containing residual chlorine from the equipment to the natural water area.
An addition device that adds a hydrogen-containing liquid containing dissolved hydrogen or gaseous hydrogen to the water in the flood bypass, and
Water treatment equipment equipped with.
The addition device
The water treatment facility according to claim 7, further comprising a gas dissolving device for producing the hydrogen-containing liquid by dissolving gaseous hydrogen in a liquid.
In addition to being connected to the natural water area, it is further equipped with an intake channel that takes in water from the natural water area.
The addition device
The water treatment facility according to claim 8, further comprising an electrolyzer that supplies the water from the intake channel, generates the gaseous hydrogen by electrolysis of the water, and sends the gaseous hydrogen to the gas dissolving apparatus.
In addition to being connected to the natural water area, it is further equipped with an intake channel that takes in water from the natural water area.
The addition device
The water according to claim 7, further comprising an electrolyzer that supplies the water from the intake channel, generates the gaseous hydrogen by electrolysis of the water, and adds the gaseous hydrogen to the water in the drainage channel. Processing equipment.
The natural water area is the sea or a salt lake, and the water taken into the intake channel is salt water.
The water treatment facility according to claim 9 or 10, wherein the electrolysis device generates a chlorine-based aqueous solution containing effective chlorine by electrolysis of the salt water, and adds the chlorine-based aqueous solution to the salt water in the intake channel.
The water treatment facility according to any one of claims 9 to 11, wherein the water is supplied from the intake channel to the facility.
The water treatment equipment according to any one of claims 7 to 12, wherein the equipment is a condenser.
A water channel that has an intake and a water outlet provided in a natural water area, takes in water from the natural water area through the water intake, and discharges the taken-in water to the natural water area through the water outlet.
A chlorine-based chemical is added to the water in the water channel at a predetermined position in the water channel, and a hydrogen-containing liquid or gaseous hydrogen containing dissolved hydrogen is added to the water in the water channel at a position closer to the outlet side than the predetermined position. Water treatment equipment equipped with an addition device.