KR20150098425A - Apparatus for treating seawater using by-product of power plant and method thereof - Google Patents

Abstract

The present invention relates to an apparatus and a method for treating seawater using by-products of a power plant and, more specifically, to an apparatus for treating seawater to desulfurize sulfur oxides contained in exhaust gas generated from a power plant with seawater. The apparatus comprises: a reaction unit which reacts seawater with by-products of the power plant; a stirring unit which stirs seawater with by-products of the power plant; an absorption unit which desulfurizes seawater by reacting seawater, which has been reacted in the reaction unit, with sulfur oxides of the power plant; a precipitation unit which regulates the pH of desulfurized seawater by reacting desulfurized seawater with seawater and precipitates desulfurized seawater and by-products of the power plant to be separated; and an oxidation unit which degasses carbon dioxide contained in desulfurized seawater. Therefore, the present invention is capable of reducing a seawater input amount when desulfurizing seawater, and shortening the time required for a desulfurization process, by supplying seawater with the increased alkalinity by by-products of the power plant in the reaction unit in a seawater desulfurization process for sulfur oxides contained in exhaust gas discharged from the power plant. Moreover, the present invention can enhance economic efficiency of the seawater desulfurization process by lowering the amount of chemicals used to regulate the pH of desulfurized seawater.

Description

Technical Field [0001] The present invention relates to an apparatus for treating seawater using power plant by-products,

The present invention relates to an apparatus and a method for treating seawater using a power plant byproduct, and more particularly, to a desulfurization apparatus for desulfurizing sulfur oxides discharged from a power plant, ≪ / RTI >

Generally, when sulfur contained in fossil fuel fuel burns sulfur oxides (SO ₂ , SO ₃ ) in the exhaust gas at about 1,000 ppm, SO ₂ is oxidized to SO ₃ in the air and then reacts with water to produce SO ₂ It is converted to contaminants such as sulfuric acid-mist (H ₂ SO ₄ -mist) which is 10 times more dangerous to human body.

Wet limestone-gypsum method and seawater desulfurization method are mainly used as a method for reducing sulfur oxides (SOx) generated from such thermal power plants. The most commonly used wet limestone-gypsum method is known to be superior in terms of technical completeness and reliability.

However, there is a problem in economic and operational aspects such as facilities for pretreatment of limestone, large initial investment cost, large installation area, and difficulty in disposing wastewater and waste.

In addition, since the seawater desulfurization method can be applied to a power plant constructed on a coastal area using a large amount of cooling water and a large amount of seawater is used as cooling water in the condenser of the boiler, the drainage of seawater discharged from the condenser And is used as an absorption liquid to remove SOx from the exhaust gas.

This seawater desulfurization process has a lower initial investment cost and stable operation compared with the lime-gypsum process, but a large amount of chemicals such as NaOH are used to restore the alkalinity and pH of the seawater, thereby deteriorating the economical efficiency.

In this way, the method of desalination of seawater is a method of removing sulfur oxides from flue gas using natural alkalinity (HCO ₃ ^- , CO ₃ ^2- , OH ^- ) contained in seawater. In order to use this method, (HCO ₃ ^- ), but the alkalinity of the seawater should not be stable due to seasonal or regional changes.

In conventional seawater desulfurization methods, NaOH or calcium hydroxide is added to increase the alkalinity to about 130 ppm. After the desulfurization, desulfurized seawater has a pH of about 2.5 or lower at a pH of about 8, so that the pH of the desalted seawater should be raised to at least 6 to discharge to the sea.

For this purpose, conventionally expensive chemicals such as NaOH, lime, magnesium hydroxide, etc. are used. However, when such expensive chemicals are used in the desalination process of the seawater, the cost of the seawater is increased because the consumption of the chemicals is large and the economic efficiency is deteriorated.

Korean Registered Patent No. 1996-0010381 (July 31, 1996) Korean Registered Patent No. 10-0701239 (March 29, 2007)

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made in order to solve the above-mentioned problems, and it is an object of the present invention to reduce the amount of seawater input during desalination of sulfuric acid contained in exhaust gas discharged from a power plant, Which is capable of improving the economical efficiency of a desalination process of a seawater by reducing the amount of chemicals used in the seawater desalination process.

The present invention also provides an apparatus for treating seawater and a method for treating seawater using a power plant by-product which can facilitate pH recovery of desulfurized seawater and shorten the treatment time of desulfurized seawater and reduce contamination of desulfurized seawater discharged to the ocean It is another purpose.

It is another object of the present invention to provide an apparatus and a method for treating seawater by reacting seawater with byproducts and putting the seawater into an absorption unit and a sedimentation unit and storing seawater raw water, The purpose.

Another object of the present invention is to provide an apparatus and method for treating seawater using power plant byproducts that can improve the reactivity while optimizing the reaction between seawater and by-products of power plants.

It is another object of the present invention to provide an apparatus and a method for treating seawater using plant byproducts that can reduce the cost of seawater desalination in seawater desulfurization by reusing the byproducts of the power plant by landfill.

It is another object of the present invention to provide an apparatus and a method for treating seawater using a byproduct of a power plant capable of recovering pH of desulfurized seawater and removing contaminants contained in desulfurized seawater.

Another object of the present invention is to provide an apparatus and method for treating sea water using a byproduct of a power plant capable of improving the pH stability of desulfurized seawater while optimizing the reaction between desulfurized seawater and seawater.

It is another object of the present invention to provide an apparatus and method for treating seawater using a by-product of a power plant that can easily remove contaminants contained in desulfurized seawater and reduce the degree of contamination of desulfurized seawater.

According to an aspect of the present invention, there is provided an apparatus for treating seawater for desulfurizing sulfur oxides contained in exhaust gas of a power plant with seawater, comprising: a reaction unit (10) for reacting seawater and power plant byproducts; A stirring part 20 provided inside the reaction part 10 and stirring to improve reactivity between seawater and power plant by-products; An absorber 30 connected downstream of the reactor 10 to desulfurize the reacted seawater by reacting with the sulfur oxide; A sedimenting unit 40 connected to the absorber 30 downstream to react the desulfurized seawater and the seawater to adjust the pH of the desulfurized seawater and precipitate the desulfurized seawater to separate the power plant byproducts; And an oxidation unit (50) connected to the downfalling part (40) to degas the carbon dioxide contained in the desulfurized seawater.

Further, the present invention is characterized by further comprising a chemical input unit (60) connected downstream of the settling unit (40) for inputting chemicals to adjust the pH of the desulfurized seawater after the reaction between the desalted seawater and the seawater do.

The reaction unit 10 of the present invention comprises a reaction tank for reacting seawater with power plant by-products and discharging it to the absorption unit 30 and the precipitating unit 40; And a storage tank for storing the seawater and discharging the seawater to the oxidation unit 50. The power plant by-product of the present invention is a fly ash or flooring material generated in a power plant.

The absorption unit (30) of the present invention comprises an absorption tower having a bottom storage tank for desulfurization by reacting seawater with sulfur oxides.

The sedimenting unit (40) of the present invention comprises a seawater recovery tank for reacting desulfurized seawater and seawater to adjust the pH of the desulfurized seawater; A sedimentation tank connected downstream of the seawater recovery tank to precipitate the desulfurized seawater and the power plant by-product to separate the desulfurized seawater from the power plant byproduct; And a filtration tank connected downstream of the sedimentation tank to repeatedly filter the separated desulfurized seawater into the sedimentation tank.

In the seawater recovery tank of the present invention, desulfurized seawater and seawater are mixed at a ratio of 1: 0.5 to 1: 1.4 and reacted to adjust the pH of the desulfurized seawater. In the settling tank of the present invention, the suspended material on the upper part of the settling tank and the settled material on the lower part of the settling tank are separated and discharged to the outside, and the supernatant of the settling tank is discharged to the oxidizing unit (50).

The present invention also provides a method of treating sea water using a by-product of a power plant using the above-described apparatus for treating seawater, comprising the steps of: mixing seawater and power plant by-products; Reacting the power plant by-products with seawater; Desulfurizing the reacted seawater by reacting with the sulfur oxide; Reacting the desulfurized seawater used in the desulfurization with seawater; Precipitating the reacted desulfurized seawater to separate power plant by-products; And degassing the carbon dioxide contained in the desulfurized seawater.

The present invention is characterized in that after the sedimentation step, diluting seawater raw water into the desulfurized seawater precipitated and separated so as to adjust the pH of the desulfurized seawater, diluting the raw desalted seawater by adding the chemical, And further comprising:

In the step of reacting the desulfurized seawater and the seawater according to the present invention, the pH of the desulfurized seawater is adjusted by mixing and reacting the desulfurized seawater with the seawater at a ratio of 1: 0.5 to 1: 1.4.

As described above, the present invention increases the alkalinity of the seawater to the power plant by-product in the reaction part during the desalination process of the sulfur oxides contained in the exhaust gas discharged from the power plant, thereby reducing the amount of seawater input during desalination of the seawater, And at the same time, it is possible to improve the economical efficiency of the desalination process by reducing the amount of chemicals used for pH adjustment of the desalted seawater.

In addition, by connecting the chemical input portion to the downstream of the settling portion, the pH of the desulfurized seawater can be easily restored, the treatment time of the desulfurized seawater can be shortened, and the contamination of the desulfurized seawater discharged into the ocean can be reduced.

Also, by providing the reaction tank and the reservoir in the reaction part, the seawater is reacted with the by-product to be introduced into the absorption part and the sediment part, and the raw water of the seawater can be stored and used for adjusting the pH of the desulfurized seawater.

In addition, the reactivity can be optimized by optimizing the reaction between the power generation by-product and the seawater by limiting the mixing ratio of the power plant by-product and the seawater to a predetermined range in the reactor and limiting the reaction time to a predetermined range.

In addition, by using fly ash or bottom material among the by-products of the power plant, it is possible to reuse the by-products of the power plant to be landfilled, thereby reducing the seawater treatment cost of the desalination process.

In addition, it is possible to remove the pollutants contained in the desulfurized seawater by pH restoration of the desulfurized seawater by installing the seawater recovery tank, the settling tank and the filtration tank sequentially in the settling portion.

In addition, in the seawater recovery tank, the reaction between the desulfurized seawater and the seawater is optimized by limiting the mixing ratio of the desulfurized seawater and the seawater to a predetermined range, thereby improving the pH stability of the desulfurized seawater.

In addition, by removing the floating material and precipitating material of the desulfurized seawater from the sedimentation tank, it is possible to facilitate the removal of the contaminants contained in the desulfurized seawater and to reduce the contamination degree of the desulfurized seawater.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an apparatus for treating sea water using a by-product of a power plant according to an embodiment of the present invention; FIG.
2 is a flow chart illustrating a method of treating sea water using a by-product of a power plant according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an apparatus for treating sea water using a by-product of a power plant according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a view illustrating a system for processing seawater using a byproduct of a power plant according to an embodiment of the present invention, and FIG. 2 is a flowchart illustrating a method for processing seawater using a byproduct of a power plant according to an embodiment of the present invention.

1, the seawater treatment apparatus using the power plant by-product according to the present embodiment includes a reaction unit 10, a stirring unit 20, an absorption unit 30, a settling unit 40, and an oxidation unit 50 ).

The reaction unit 10 reacts the seawater with by-products of the power plant, and reacts with the fly ash or bottom material of the by-products generated from the thermal power plant to increase the alkalinity of the seawater. The sea water inflow pipe 11, A byproduct inflow pipe 15, a by-product tank 16, and a reaction tank 17.

As a by-product of such a power plant, bottom ash or fly ash of a coal-fired power plant is composed of coal fly ash remaining after combustion of coal in a power plant, 26 to 50% for anthracite coal, 8 to 15 %, And it can be divided into flooring material or fly ash depending on the place where it is gathered after combustion.

Particularly, the coal fly ash is a mixture of porous spherical particles, hard spherical particles, and indefinite particles. The particle size of the coal fly ash is usually about 1.0 to 150 mu m, and the average particle size is about 20 to 30 mu m, .

The chemical composition of the coal fly ash is that the typical composition of the bituminous coal is 85% or more of the sum of silica (SiO ₂ ) and alumina (Al ₂ O ₃ ) and 2 to 3% of the calcium oxide (CaO) The magnesium oxide (MgO) component is approximately 1%.

The seawater inflow pipe 11 is a pipe member for introducing the seawater raw water from the ocean and has a first water pump 12 and a storage tank 14 which are branched downstream of the seawater inflow pipe 11 to the reaction tank 17 And a second water pump 13 for branching and pumping is provided.

The storage tank 14 is a storage means connected to the downstream of the second water pump 13 for storing seawater and the seawater stored in the storage tank 14 is discharged to the absorption portion 30 or discharged to the oxidation portion 50 .

The byproduct inflow pipe 15 is a pipe member through which fly ash or bottom material flows in the byproducts generated in the thermal power plant. A byproduct tank 16 for temporarily storing the byproduct is provided downstream of the byproduct inflow pipe 15.

The reaction tank 17 is reaction means connected downstream of the first water pump 12 and connected downstream of the by-product tank 16, and reacts the seawater with power plant by-products to increase the alkalinity of the seawater.

In the reaction tank 17, the by-product of the power plant and the seawater are preferably mixed at a ratio of 1: 2000 to 1: 100 and reacted for 1 minute to 60 minutes. If the mixing ratio of the by-product and the sea water is lower than 1: 2000, the synergy of the alkalinity of the seawater is insignificant. If the mixing ratio of the by-product and the seawater is less than 1: 2000, the increase of the alkalinity of the seawater is easy. .

If the mixing time of the by-product and the seawater is shorter than 1 minute, the synergy of the alkalinity of the seawater is insignificant. If the mixing time of the seawater is longer than 60 minutes, the increase of the alkalinity of the seawater is facilitated. However, .

In addition, a feed pump may be provided downstream of the reaction tank 17 to discharge the seawater reacted with the by-product of the power plant to the absorber 30, and to appropriately adjust the discharge amount of the seawater.

The agitating unit 20 includes an agitator installed in the reaction tank 17 of the reaction unit 10 to agitate seawater and power plant byproducts at a constant rate to improve the reactivity between seawater and power plant byproducts.

The absorber 30 is connected to the downstream of the reactor 10 and is desulphurization means for desulfurizing sulfuric acid contained in the exhaust gas discharged from the power plant and sea water reacted with the by- An exhaust gas inlet 32, an agitator 33, and a heat exchanger 34.

The absorption tower 31 is provided with a storage tank at the bottom for desulfurization by reacting seawater reacted with the by-product of the power plant and sulfur oxides contained in the exhaust gas of the power plant, and a spray tube for spraying seawater at the top is provided.

The flue-gas inlet 32 is an inflow means provided at the lower part of the absorption tower 31. The flue-gas discharged from the power plant flows into the flue-gas outlet 32 and is discharged upward through an outlet of the flue-

The agitator 33 stirs the desulfurized seawater that has been subjected to the desulfurization treatment by reacting with the sulfur oxides contained in the exhaust gas of the power plant as agitation means provided in the storage tank formed in the lower part of the absorption tower 31.

The heat exchanger (34) is a gas heater provided so that an exhaust gas pipe provided upstream of the exhaust gas inlet (32) and an exhaust gas pipe provided downstream of the exhaust gas outlet communicate with each other, and the waste heat of the exhaust gas is used to heat the gas.

The sedimenting unit 40 is connected to the downstream of the absorption unit 30 to adjust the pH of the desulfurized seawater by reacting the desulfurized seawater and the seawater to separate the desulfurized seawater and the by- (41), a settling tank (42), and a filtration tank (45).

The seawater recovery tank 41 is a means for recovering the pH of the desalted seawater and the pH of the desulfurized seawater by reacting the desulfurized seawater with the seawater reacted with the by-product in the reaction unit 10 so as to improve the reactivity between the desulfurized seawater and the seawater. At the lower portion of the sea water restoration tank 41, a distribution pipe for introducing air from the air supply means 43 is provided.

In this seawater recovery tank 41, desulfurized seawater and sea water are preferably mixed at a ratio of 1: 0.5 to 1: 1.4 and reacted to adjust the pH of the desulfurized seawater to 3.5 or more. If the mixing ratio of the desalted seawater to the seawater is lower than 1: 0.5, the pH adjustment time of the desalted seawater is excessively required. If the mixing ratio is higher than 1: 1.4, the pH adjustment time of the desalted seawater is shortened, This is because the fluidity of seawater is reduced.

The sedimentation tank 42 is connected to the downstream of the seawater recovery tank 41 and is settling means for precipitating the desulfurized seawater and the byproducts of the power plant so as to separate the sedimentation tank 42 from the sedimentation tank 42. The sedimentation tank 42 discharges suspended substances, The sediment at the lower part of the settling tank 42 is separated using the chain plate and discharged to the outside through the vacuum filter 44 and the remaining desulfurized seawater is returned to the settling tank 42 to be repulsed, And the seawater is discharged to the filtration tank 45.

The filtration tank 45 is filtration means connected downstream of the settling tank 42 and repeatedly filtering the desulfurized seawater separated in the sedimentation tank 42. The desulfurized seawater is repeatedly filtered to remove foreign substances contained in the desulfurized seawater And is discharged to the oxidation section 50.

The oxidizing unit 50 is connected to the downstream of the settling unit 40 and is oxidizing means for degassing the carbon dioxide (CO ₂ ) contained in the desulfurized seawater by external air input. The oxidizing unit 50 includes a degassing vessel 51, 52, a blower 53, a distribution pipe 54, and a drain pipe 55.

The oxidation unit 50 is also connected to the downstream of the storage tank 14 of the reaction unit 10 to dilute the desulfurized seawater with the seawater raw water by mixing the desulfurized seawater and the seawater raw water of the storage tank 14, It is also possible to adjust the pH of the water by dilution with the seawater raw water.

The degassing vessel 51 is connected to the downstream of the precipitating section 40 and is a degassing means for degassing carbon dioxide (CO ₂ ) contained in the desulfurized seawater. The degassing vessel 51 is provided with an external air- The air is supplied through the blower 53 to the inner bottom of the degassing vessel 51 and the air is supplied to the inner bottom of the degassing vessel 51. In the downstream of the degassing vessel 51, And a drain pipe 55 is connected to the desalted seawater deaerated by the air to be discharged to the ocean.

Therefore, in the oxidizing section 50, the desulfurized seawater is mixed with the seawater raw water to dilute it to adjust the pH of the desulfurized seawater, and at the same time, air is supplied from the outside into the degassing vessel 51 to degas the desulfurized seawater and discharge it to the ocean.

As shown in FIG. 1, the apparatus for treating sea water using the power plant by-product of the present embodiment is connected to the down stream of the sedimentation unit 40 and is used to adjust the pH of the desulfurized seawater after the reaction between the desulfurized seawater and the seawater. It is also possible to further include the charging unit 60.

The chemical feed section 60 is connected downstream of the settling section 40 and is connected upstream of the oxidizing section 50 to adjust the pH of the desulfurized seawater after the reaction of the desulfurized seawater and the seawater in the settling section 40 A medicine supply pipe 61, a medicine storage tank 62, and a charging pump 63. The medicine supply pipe 61,

The chemical storage tank 62 is a storage means for storing chemicals for inputting a predetermined amount of medicine such as sodium hydroxide (NaOH) to precisely adjust the pH of the desulfurized seawater. And a feed pump 63 is provided downstream of the chemical reservoir 62 to regulate the amount of chemical feed according to the pH of the desulfurized seawater.

Therefore, when the desulfurized seawater is not restored to a proper pH after the reaction between the desulfurized seawater and the seawater in the sedimentation section 40, or when the desulfurized seawater and the seawater are diluted in the oxidizing section 50 When the desulfurized seawater is not restored to an appropriate pH, a chemical such as sodium hydroxide (NaOH) is added to increase the pH of the desulfurized seawater.

That is, when the desulfurized seawater is restored to a proper pH after the reaction between the desulfurized seawater and the seawater in the settling unit 40, or when the desulfurized seawater is diluted by the dilution reaction with the desulfurized seawater and the seawater in the oxidized unit 50, It is of course possible to discharge the desulfurized seawater to the ocean without the medicament input by the medicament introducing section 60.

Hereinafter, a method of treating sea water using a by-product of a power plant according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIGS. 1 and 2, the method of treating seawater using a power plant by-product using the apparatus for treating seawater according to the present embodiment includes steps of stirring seawater and byproduct (S10), reaction step of seawater and byproduct (S20) S30), a desulfurization seawater and a seawater reaction step (S40), a precipitation step (S50), and a degassing step (S70).

The step S10 of stirring the seawater and the byproduct is a step of stirring the seawater and the byproduct of the power plant at a constant speed by means of a stirrer so as to improve the reactivity between the seawater and the by- Is stirred by a stirrer.

The reaction step (S20) of the seawater and the byproduct is a step of reacting the seawater and the by-product of the power plant, and reacts fly ash or bottom material and seawater among the by-products generated from the thermal power plant to increase the alkalinity of the seawater.

In the sea water and by-product reaction step (S20), it is preferable to mix the by-product of the power plant and the sea water at a ratio of 1: 2000 to 1: 100 and react for 1 minute to 60 minutes. If the mixing ratio of the by-product and the sea water is lower than 1: 2000, the synergy of the alkalinity of the seawater is insignificant. If the mixing ratio of the by-product and the seawater is less than 1: 2000, the increase of the alkalinity of the seawater is easy. .

If the mixing time of the by-product and the seawater is less than 1 minute, the synergy of the alkalinity of the seawater is insignificant. If the mixing time of the seawater is longer than 60 minutes, the alkalinity of the seawater is increased.

The desulfurization step (S30) is a step of desulfurizing the sulfur oxides by reacting the seawater having increased alkalinity in the reaction step (S20) with the sulfur oxides contained in the exhaust gas discharged from the power plant, And the seawater and sulfur oxides react with each other in an absorption tower having a bottom storage tank.

The reaction of the desulfurization process in the absorption tower proceeds as shown in the following reaction formula (1).

[Reaction Scheme 1]

NaHCO ₃ + SO x -> NaHSO ₃ + CO ₂

The detailed reaction path of the desulfurization step is shown in Reaction Schemes 2 to 4.

[Reaction Scheme 2]

SO ₂ + H ₂ O → HSO ₃ ^- + H ⁺

HSO ₃ ^- ↔ SO ₃ ^2- + H ⁺ (reacts with SO _{2 in} flue gas)

[Reaction Scheme 3]

HSO ₃ ^- + ½O ₂ ^- > SO ₄ ^2- + H ⁺

SO ₃ ^- + ½O ₂ → SO ₄ ^2- (reacted with O _{2 in} exhaust gas)

[Reaction Scheme 4]

CO ₂ (L) + H ₂ O ↔ HCO ₃ ^- + H ⁺

HCO ₃ ^- ↔ CO ₃ ^2- + H ⁺ (reacts with CO _{2 in} flue gas)

In the desulfurization step (S30), desulfurization is preferably carried out by reacting the seawater and the sulfur oxide, and the desulfurization is preferably carried out in the absorption tower or by a dust collector installed separately on the outside.

The desulfurization seawater and the seawater reaction step S40 may include a primary recovery step of reacting the desulfurized seawater discharged in the desulfurization step S30 and the seawater having increased alkalinity in the reaction step S20, , The desulfurized seawater is reacted with the seawater having an increased alkalinity to increase the pH of the desulfurized seawater.

In the desulfurized seawater and the seawater reaction step S40, it is preferable to adjust the pH of the desulfurized seawater to 3.5 or more by mixing the desulfurized seawater with the seawater at a ratio of 1: 0.5 to 1: 1.4.

If the mixing ratio of the desalted seawater to the seawater is lower than 1: 0.5, the pH adjustment time of the desalted seawater is excessively required. If the mixing ratio is higher than 1: 1.4, the pH adjustment time of the desalted seawater is shortened, This is because the fluidity of seawater is reduced.

The sedimentation step (S50) is a step of precipitating in the sedimentation tank so as to separate the power plant by-products from the desulfurized seawater reacted with the seawater in the seawater reaction step (S40) with the desulfurized seawater. And the desulfurized seawater, which is the supernatant of the sedimentation tank, is discharged to the deaeration step (S70), which is a post-process.

The degassing step (S70) is a step of degassing the carbon dioxide contained in the desulfurized seawater separated in the sedimentation step (S50) from the degassing tank. The desulfurized seawater is deaerated by introducing air from the outside into the degassing tank, .

The reaction of the degassing process in the degassing tank proceeds as shown in the following reaction formula (5).

[Reaction Scheme 5]

NaHSO ₃ + ½O ₂ → NaHSO ₄

2NaHCO _{3 -} > Na ₂ CO ₃ + CO ₂

The detailed reaction path of the deaeration process is shown in Reaction Schemes 6 to 7.

[Reaction Scheme 6]

HSO ₃ ^- + ½O ₂ ^- > SO ₄ ^2- + H ⁺

SO ₃ ^- + ½O ₂ → SO ₄ ^2- (reacts with O _{2 in} the air to be injected)

[Reaction Scheme 7]

CO ₃ ^2- + H ⁺ ↔ HCO ₃ ^-

HCO ₃ ^- + H ⁺ ↔ CO ₂ (L) + H ₂ O (degassing CO ₂ )

In addition, the method of treating seawater using the power plant by-product of the present embodiment is characterized in that seawater is supplied to desulfurized seawater precipitated and separated so as to adjust the pH of the desulfurized seawater between the settling step (S50) and the degassing step (S70) (S60) of injecting medicines, diluting the raw water with the seawater, and injecting the medicines.

The step S60 of adding the chemical is a second restoration step of adjusting the pH of the desulfurized seawater to the second level by introducing chemical and seawater raw water after the reaction between the desulfurized seawater and the seawater whose alkalinity is increased in the seawater reaction step S40 If the pH of the desulfurized seawater does not reach the appropriate desulfurized seawater pH in the desulfurized seawater and the seawater reaction step (S40), chemicals such as sodium hydroxide (NaOH) or the like may be added or the seawater may be added to adjust the pH of the desulfurized seawater.

In addition, the chemical input step S60 is a step in which, after the reaction between the desulfurized seawater and the seawater whose alkalinity has been increased in the seawater reaction step S40, the seawater is first introduced to adjust the pH of the desulfurized seawater, It is of course possible to adjust the pH of the desulfurized seawater.

[Example]

Generally, in a 500 MW coal-fired power plant, 13 to 20 ton / hr of fly ash and 1.3 to 2.0 ton / hr of bottom ash are generated depending on the fuel properties. Examples of experiments for increasing alkalinity of seawater and restoring pH of desulfurized seawater using the same are as follows.

[Experimental Study on Alkalinity of Seawater Before Desulfurization]

Alkalinity of seawater is increased by controlling the ratio of fly ash and sea water, based on the amount of fly ash (13 ton / hr) that can be generated in a 500 MW thermal power plant and the amount of seawater used for desalination of sea water (24,000 ton / hr) .

When the ratio of fly ash and sea water was 1: 2000, the initial alkalinity increased from 110 to 127 as time passed. In case of the ratio of fly ash and sea water of 1: 200, the alkalinity was greatly increased from 110 to 155.

[Experiments for restoration of pH of seawater after desulfurization]

The pH of desulfurized seawater after desulfurization is known to be around 2.5 ~ 3.5. Experiments were carried out by adjusting the amount of fly ash to 1: 2000, 1: 200, 1: 100, etc. based on pH 2.69. As a result, the pH rose from a maximum of 2.69 to 5.86.

The amount of fly ash was fixed and the pH of the desalted seawater was changed to 2.5, 3.0, and 3.5, and the pH of the desalted seawater was restored over time. As a result, it was possible to restore the pH from 4.92 to 6.48 at 1:40.

[PH restoration experiment of seawater and desulfurized water]

In the seawater desulfurization process, the seawater is introduced into the absorption tower and the deaeration tank at a ratio of about 1: 1, respectively. Therefore, when the pH of the desulfurized seawater is 3.5 and the pH of the desalinated seawater is 8 or more, the pH of the desulfurized seawater can be adjusted to 6 or more.

As described above, according to the present invention, by increasing the alkalinity of the seawater to the power plant byproduct in the reactor during the desulfurization process of the sulfur oxides contained in the exhaust gas discharged from the power plant, it is possible to reduce the amount of seawater input during desalination of the seawater, And at the same time, it is possible to improve the economical efficiency of the desalination process by reducing the amount of chemicals used for pH adjustment of the desalted seawater.

In addition, by connecting the chemical input portion to the downstream of the settling portion, the pH of the desulfurized seawater can be easily restored, the treatment time of the desulfurized seawater can be shortened, and the contamination of the desulfurized seawater discharged into the ocean can be reduced.

Also, by providing the reaction tank and the reservoir in the reaction part, the seawater is reacted with the by-product to be introduced into the absorption part and the sediment part, and the raw water of the seawater can be stored and used for adjusting the pH of the desulfurized seawater.

In addition, the reactivity can be optimized by optimizing the reaction between the power generation by-product and the seawater by limiting the mixing ratio of the power plant by-product and the seawater to a predetermined range in the reactor and limiting the reaction time to a predetermined range.

In addition, by using fly ash or bottom material among the by-products of the power plant, it is possible to reuse the by-products of the power plant to be landfilled, thereby reducing the seawater treatment cost of the desalination process.

In addition, it is possible to remove the pollutants contained in the desulfurized seawater by pH restoration of the desulfurized seawater by installing the seawater recovery tank, the settling tank and the filtration tank sequentially in the settling portion.

In addition, in the seawater recovery tank, the reaction between the desulfurized seawater and the seawater is optimized by limiting the mixing ratio of the desulfurized seawater and the seawater to a predetermined range, thereby improving the pH stability of the desulfurized seawater.

In addition, by removing the floating material and precipitating material of the desulfurized seawater from the sedimentation tank, it is possible to facilitate the removal of the contaminants contained in the desulfurized seawater and to reduce the contamination degree of the desulfurized seawater.

The present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Therefore, the above embodiments are merely illustrative in all respects and should not be construed as limiting.

10: Reactor 20: Agitator
30: absorbing part 40:
50: oxidation part 60: drug introduction part

Claims (11)

An apparatus for treating seawater for desulfurizing sulfur oxides contained in flue gas of a power plant with seawater,
A reaction unit 10 for reacting seawater and power plant by-products;
A stirring part 20 provided inside the reaction part 10 and stirring to improve reactivity between seawater and power plant by-products;
An absorber 30 connected downstream of the reactor 10 to desulfurize the reacted seawater by reacting with the sulfur oxide;
A sedimenting unit 40 connected to the absorber 30 downstream to react the desulfurized seawater and the seawater to adjust the pH of the desulfurized seawater and precipitate the desulfurized seawater to separate the power plant byproducts; And
And an oxidizing part (50) connected to the downfalling part (40) to degas the carbon dioxide contained in the desulfurized seawater. The method according to claim 1,
(60) connected to the downfalling part (40) downstream of the precipitating section (40) for inputting the chemical to adjust the pH of the desulfurized seawater after the reaction between the desulfurized seawater and the seawater Processing device for seawater. The method according to claim 1,
The reaction part (10)
A reaction tank which reacts seawater with power plant byproducts and discharges the absorbing portion 30 and the precipitating portion 40; And
And a storage tank for storing the seawater and discharging the seawater to the oxidation unit (50). The method according to claim 1,
Wherein the power plant by-product is a fly ash or flooring material generated in a power plant. The method according to claim 1,
Wherein the absorber (30) comprises an absorption tower having a bottom storage tank for desulfurization by reacting seawater with sulfur oxides. The method according to claim 1,
The sinking part (40)
A seawater recovery tank for reacting the desulfurized seawater and the seawater to adjust the pH of the desulfurized seawater;
A sedimentation tank connected downstream of the seawater recovery tank to precipitate the desulfurized seawater and the power plant by-product to separate the desulfurized seawater from the power plant byproduct; And
And a filtration tank connected downstream of the sedimentation tank to repeatedly filter the desulfurized seawater separated from the sedimentation tank. The method according to claim 6,
Wherein the seawater recovery vessel mixes the desulfurized seawater and the seawater at a ratio of 1: 0.5 to 1: 1.4 and reacts them to adjust the pH of the desulfurized seawater. 8. The method of claim 7,
Wherein the sedimentation tank separates the suspended material on the upper part of the sedimentation tank and the sediment under the sedimentation tank, discharges the sediment to the outside, and discharges the supernatant of the sedimentation tank to the oxidation part (50). A method of treating sea water using a by-product of a power plant using the apparatus for treating seawater according to claim 1,
Stirring seawater and power plant byproducts;
Reacting the power plant by-products with seawater;
Desulfurizing the reacted seawater by reacting with the sulfur oxide;
Reacting the desulfurized seawater used in the desulfurization with seawater;
Precipitating the reacted desulfurized seawater to separate power plant by-products; And
And deasphalting the carbon dioxide contained in the desulfurized seawater. 10. The method of claim 9,
Adding the raw water to the desalted seawater so as to adjust the pH of the desulfurized seawater so as to adjust the pH of the desulfurized seawater and diluting the raw desalted raw water, Wherein the method comprises the steps of: 10. The method of claim 9,
Wherein the step of reacting the desulfurized seawater with the seawater comprises mixing the desulfurized seawater and the seawater at a ratio of 1: 0.5 to 1: 1.4 and reacting them to adjust the pH of the desulfurized seawater.

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