JP2013154329A - Seawater exhaust gas desulfurization system, and power generator system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a seawater exhaust gas desulfurization system for efficiently treating sulfur component absorbing seawater and reducing the size of an oxidation tank, and a power generator system.SOLUTION: A seawater exhaust gas desulfurization system 10 includes an exhaust gas desulfurization absorbing column 11 for bringing exhaust gas 25 into gas-liquid contact with absorbing seawater 21a to wash exhaust gas 25 and an aeration device 41 provided downstream of the exhaust gas desulfurization absorbing column 11 to supply air 29 to sulfur component-containing sulfur component absorbing seawater 14 and has an oxidation tank 12 for performing the water quality restoring treatment of the sulfur component absorbing seawater 14, a seawater supply line L11 for supplying seawater 21 to the exhaust gas desulfurization absorbing column 11, and an air branch line L12 for supplying a part of the air 29 supplied to the oxidation tank 12 to a column bottom part 11a of the exhaust gas desulfurization absorbing column 11.

Description

  The present invention relates to a seawater flue gas desulfurization system and a power generation system that oxidize sulfur-absorbed seawater generated by desulfurization of sulfur contained in exhaust gas using seawater.

In power plants that use coal or crude oil as fuel, combustion exhaust gas (hereinafter referred to as “exhaust gas”) discharged from boilers by burning fossil fuels such as coal contains sulfur components such as sulfur oxide (SOx). included. Therefore, the exhaust gas is desulfurized and released to the atmosphere after removing sulfur oxides (SOx) such as sulfur dioxide (SO ₂ ) contained in the exhaust gas. Examples of such a desulfurization method include a lime gypsum method, a spray dryer method, and a seawater method.

  Power plants are often constructed in locations facing the sea because they require a large amount of cooling water. For this reason, a seawater flue gas desulfurization apparatus using seawater desulfurization that performs desulfurization using seawater as an absorbing liquid that absorbs sulfur oxide in exhaust gas has been proposed from the viewpoint of suppressing the operating cost required for the desulfurization treatment. Yes.

Seawater flue gas desulfurization equipment supplies seawater and boiler exhaust gas into a desulfurization tower (absorption tower) that has a cylindrical shape or a rectangular shape such as a substantially cylindrical shape placed vertically, and makes seawater gas-liquid contact as an absorption liquid. SOx is removed. Seawater after desulfurization (sulfur content-absorbing seawater) used as an absorbent in the desulfurization tower is supplied to the oxidation tank. The sulfur-absorbing seawater flowing in the oxidation tank is diluted with seawater that is not used for desulfurization. In addition, the sulfur-absorbing seawater is decarboxylated (exploded) by fine bubbles flowing out from an aeration apparatus (aeration apparatus) installed on the bottom surface of the oxidation tank (see, for example, Patent Document 1). As a result, the sulfur-absorbing seawater is discharged after being subjected to SO ₃ oxidation and CO ₂ explosion treatment so as to satisfy local environmental standards.

JP 2007-125474 A

  In general, the oxidation tank is a long water channel (Seawater Oxidation Treatment System; SOTS) having an open top of about 20 m to 40 m in width and about 100 m to 200 m in length, and requires a large installation area. In the oxidation tank, oxygen is supplied in the state of air from the aeration apparatus provided at the bottom of the oxidation tank to almost the entire bottom of the oxidation tank.

Conventionally used oxidation tanks supply oxygen in the state of air to sulfur-absorbing seawater flowing through the oxidation tank from the entire bottom surface of the oxidation tank, so the power cost required to operate the oxidation tank is high. . In addition, there is a place where more oxygen than necessary for the oxidation of SO ₃ in the sulfur-absorbing seawater and the explosion of CO ₂ is supplied, and oxygen is supplied more than necessary. The oxidation of SO ₃ and the explosion of CO ₂ are not efficient and not performed.

  Therefore, there is a need for a seawater flue gas desulfurization system that efficiently treats sulfur-absorbing seawater and reduces the size of the oxidation tank.

  In view of the above problems, an object of the present invention is to provide a seawater flue gas desulfurization system and a power generation system that efficiently process sulfur-absorbing seawater and reduce the size of an oxidation tank.

  The first invention of the present invention for solving the above-mentioned problems is a flue gas desulfurization absorption tower that cleans the flue gas by contacting the exhaust gas and seawater in a gas-liquid manner, and a downstream side of the flue gas desulfurization absorption tower. Provided with an air supply means for supplying air to sulfur-absorbing seawater containing sulfur, and supplying the sulfur-absorbing seawater to the flue gas desulfurization absorption tower, an oxidation tank for performing water quality recovery treatment of the sulfur-absorbing seawater A seawater flue gas desulfurization system comprising: a seawater supply line; and an air branch line for supplying a part of the air supplied to the oxidation tank to the bottom of the flue gas desulfurization absorption tower.

  2nd invention has the diluted seawater branch line which branches from the said seawater supply line in 1st invention, and supplies a part of said seawater to the tower bottom part of said flue gas desulfurization absorption tower as diluted seawater. This is a seawater flue gas desulfurization system.

The third invention is the first or second aspect of the present invention, SO ₂ absorption amount to the total amount of the seawater supplied to the flue gas desulfurization absorber tower, seawater flue gas to equal to or less than 3 mmol / l Desulfurization system.

  A fourth invention is the seawater flue gas desulfurization system according to any one of the first to third inventions, wherein the temperature of the sulfur-absorbing seawater is 5 ° C or higher and 55 ° C or lower.

  A fifth invention is the seawater flue gas desulfurization system according to any one of the first to fourth inventions, wherein the pH of the seawater is 5.5 or more.

According to a sixth invention, in any one of the first to fifth inventions, for measuring an inlet SO ₂ concentration and an outlet SO ₂ concentration of the exhaust gas at the exhaust gas inlet and outlet of the flue gas desulfurization absorption tower. An SO ₂ concentration meter, a seawater circulation line that circulates the sulfur-absorbing seawater in the flue gas desulfurization absorption tower to the seawater supply line, and the seawater circulation line that is extracted from the flue gas desulfurization absorption tower A flow meter for measuring the flow rate of the sulfur-absorbing seawater, and calculating a desulfurization rate in the flue gas desulfurization absorption tower based on an inlet SO ₂ concentration and an outlet SO ₂ concentration of the exhaust gas, and the dilution It is a seawater flue gas desulfurization system characterized by adjusting a supply amount of seawater supplied to the oxidation tank via a seawater branch line.

  The seventh invention uses a boiler, a steam turbine that uses the exhaust gas discharged from the boiler as a heat source for generating steam, drives a generator using the generated steam, and any one of first to sixth A seawater flue gas desulfurization system of one invention, a condenser that collects and circulates water condensed by the steam turbine, a flue gas denitration device that denitrates exhaust gas discharged from the boiler, It is a power generation system characterized by having a dust collector which removes soot and dust.

  According to the present invention, it is possible to efficiently treat sulfur-absorbing seawater and reduce the size of the oxidation tank.

FIG. 1 is a schematic diagram showing the configuration of a seawater flue gas desulfurization system according to Example 1 of the present invention. FIG. 2 is a schematic diagram illustrating a configuration of a power generation system according to a second embodiment of the present invention.

  Hereinafter, the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by the following Example. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those in a so-called equivalent range. Furthermore, the constituent elements disclosed in the following embodiments can be appropriately combined.

  A seawater flue gas desulfurization system according to Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the configuration of a seawater flue gas desulfurization system according to Example 1 of the present invention. As shown in FIG. 1, the seawater flue gas desulfurization system 10 according to the present embodiment includes a flue gas desulfurization absorption tower 11, an oxidation tank 12, a seawater supply line L11, and an air branch line L12.

  The seawater 21 is pumped from the sea 22 to the seawater supply line L11 by the pump 22a, and a part of the seawater 21 is supplied to the flue gas desulfurization absorption tower 11 via the seawater supply line L11 by the pump 22b as the absorbed seawater 21a. A part of the seawater 21 is supplied as diluted seawater 21b to the oxidation tank 12 via the diluted seawater supply line L13, and a part of the diluted seawater 21b is supplied as diluted seawater 21c to the oxidation tank 12 via the diluted seawater supply line L14. Is done. The supply amounts of the diluted seawaters 21b and 21c flowing in the diluted seawater supply lines L13 and L14 are adjusted by the pumps 22c and 22d.

  Although the seawater 21 uses the seawater pumped directly from the sea 22 by the pump 22a, the present embodiment is not limited to this, and uses the drainage of the seawater 21 discharged from a condenser (not shown). You may do it.

  The flue gas desulfurization absorption tower 11 is a tower for purifying the exhaust gas 25 by gas-liquid contact between the exhaust gas 25 and the absorbed seawater 21a. In the flue gas desulfurization absorption tower 11, the absorbed seawater 21a is ejected in a liquid column shape above the spray nozzle 26, and the exhaust gas 25 and the seawater 21a supplied via the seawater supply line L11 are brought into gas-liquid contact. Desulfurization of sulfur content. In the present embodiment, the spray nozzle 26 is a spray nozzle that ejects upward in the form of a liquid column, but is not limited thereto, and may be sprayed downward in the form of a shower.

In this specification, the sulfur content refers to a sulfur concentration (mass ppm or mass ppb) obtained by converting the concentration of all sulfur compounds contained in hydrocarbon oil into a sulfur atom, and specifically, for example, SO ₂ , SOx such as SO ₃ and sulfite ion (SO ₃ ) can be used.

That is, in the flue gas desulfurization absorption tower 11, the exhaust gas 25 and the absorbed seawater 21a are brought into gas-liquid contact to cause a reaction as shown in the following formula (I) and contained in the form of SO ₂ in the exhaust gas 25. The sulfur content such as SOx is absorbed by the absorption seawater 21a, and the sulfur content in the exhaust gas 25 is removed using the seawater 21a.
SO ₂ (g) + H ₂ O → H ₂ SO ₃ (l) → HSO ₃ ⁻ + H ⁺ (I)

Due to this seawater desulfurization, H ₂ SO ₃ generated by gas-liquid contact between the absorbed seawater 21a and the exhaust gas 25 is dissociated and hydrogen ions (H ⁺ ) are released into the absorbed seawater 21a. Contains a high sulfur content. At this time, as pH of the sulfur content absorption seawater 14, it will be about 3-6, for example. And the sulfur content absorption seawater 14 which absorbed the sulfur content in the flue gas desulfurization absorption tower 11 is stored in the tower bottom part of the flue gas desulfurization absorption tower 11.

  Further, the purified gas 28 desulfurized in the flue gas desulfurization absorption tower 11 is released into the atmosphere through the purified gas discharge passage L15.

  The seawater flue gas desulfurization system 10 according to the present embodiment has an air branch line L12 that supplies a part of the air 29 supplied to the oxidation tank 12 to the bottom of the flue gas desulfurization absorption tower 11. By supplying the air 29 extracted to the air branch line L12 to the tower bottom (absorption tower tank) 11a of the flue gas desulfurization absorption tower 11, the amount of dissolved oxygen in the sulfur-absorbing seawater 14 in the flue gas desulfurization absorption tower 11 Can be increased. For this reason, in the oxidation tank 12 provided on the downstream side of the flue gas desulfurization absorption tower 11, the sulfur-absorbing seawater 14 can be processed efficiently, and it is necessary to perform the water quality recovery process of the sulfur-absorbing seawater 14. The blowing distance of the air 29 can be shortened. Therefore, by shortening the blowing distance of the air 29 in the oxidation tank 12, the distance in the length direction of the oxidation tank 12 that is the flow direction of the sulfur-absorbing seawater 14 can be shortened, so the size of the oxidation tank 12 is reduced. can do.

  The air 29 extracted to the air branch line L12 is supplied to the flue gas desulfurization absorption tower 11 by the blower 22e. The method of supplying the air 29 to the oxidation tank 12 via the air branch line L12 is not limited to the blower 22e, and the vicinity of the connecting portion connected to the oxidation tank 12 of the air branch line L12 is an orifice shape. Alternatively, the air 29 may be supplied into the oxidation tank 12.

  The seawater flue gas desulfurization system 10 according to the present embodiment branches from the diluted seawater supply line L13, and a part of the diluted seawater 21b supplied to the oxidation tank 12 is used as diluted seawater 21c at the bottom of the flue gas desulfurization absorption tower 11. A diluted seawater branch line L14 is provided. Generally, since the pH in the flue gas desulfurization absorption tower 11 is low, sulfur content such as sulfite ions dissolved in the sulfur content absorption seawater 14 is not oxidized, but diluted seawater 21c is added to the absorption tower tank 11a of the flue gas desulfurization absorption tower 11. Is directly supplied, the pH of the sulfur-absorbing seawater 14 is increased, and the oxidation of sulfur such as sulfite ions dissolved in the sulfur-absorbing seawater 14 stored in the absorption tower tank 11a can be promoted. . Further, by supplying the diluted seawater 21c to the absorption tower tank 11a of the flue gas desulfurization absorption tower 11 and diluting the sulfur-absorbing seawater 14, the sulfur-absorbing seawater 14 is caused by air entrainment when the sulfur-absorbing seawater 14 falls. Oxygen can be taken in, and the effect of promoting the oxidation of sulfur components such as sulfite ions dissolved in the sulfur-absorbing seawater 14 can be obtained. Therefore, when the diluted seawater 21c is supplied into the absorption tower tank 11a of the smoke desulfurization absorption tower 11, the oxidation in the flue gas desulfurization absorption tower 11 is compared with the case where the diluted seawater 21c is not supplied into the smoke desulfurization absorption tower 11. However, the oxidation in the flue gas desulfurization absorption tower 11 is promoted, for example, and the length of the oxidation tank 12 provided on the downstream side of the flue gas desulfurization absorption tower 11 can be shortened. Thereby, the magnitude | size of the oxidation tank 12 can be reduced.

SO ₂ absorption (ΔToS (SO ₂ absorption / total amount of seawater)) relative to the total amount of seawater 21a and diluted seawater 21b supplied to the flue gas desulfurization absorption tower 11 via the seawater supply lines L11 and L13 is 3 mmol / l or less. More preferably, it is 2 mmol / l or less, and more preferably 1 mmol / l or less. When ΔToS is 3 mmol / l or less, the pH of the sulfur-absorbing seawater 14 is 4.0 or more, and an effect of promoting the oxidation of sulfur components such as sulfite ions dissolved in the yellow-absorbing seawater 14 is obtained. If ΔToS is 2 mmol / l or less, the effect of promoting the oxidation of the sulfur content is high, and if ΔToS is 1 mmol / l or less, the effect is further enhanced.

  The temperature of the seawater is preferably 5 ° C. or higher and 55 ° C. or lower, more preferably 15 ° C. or higher, and further preferably 30 ° C. or higher. When the temperature of the seawater is 5 ° C. or higher, an effect of increasing the oxidation rate is obtained by the temperature increase, and when the temperature of the seawater is 15 ° C. or higher, the oxidation rate is further increased. An effect is more acquired and a higher effect is acquired when the temperature of seawater is 30 degreeC or more.

  It is preferable that pH of the sulfur content absorption seawater 14 is 4.0 or more and 8.3 or less, More preferably, it is 5.5 or more. If the pH of the sulfur-absorbing seawater 14 is 4.0 or more, the effect of promoting the oxidation of sulfur such as sulfite ions dissolved in the yellow-absorbing seawater 14 can be obtained. In the case of 5.5 or more, a higher effect can be obtained.

SO ₂ concentration meters 32 a and 32 b for measuring the inlet SO ₂ concentration and the outlet SO ₂ concentration of the exhaust gas 25 are provided on the inlet side and the outlet side of the exhaust gas 25 of the flue gas desulfurization absorption tower 11. The flue gas desulfurization absorption tower 11 is provided with a seawater circulation line L16 for circulating the sulfur-absorbing seawater 14 in the flue gas desulfurization absorption tower 11 to the seawater supply line L11. The seawater circulation line L16 is provided with a flow meter 33 for measuring the flow rate of the sulfur-absorbing seawater 14 extracted from the flue gas desulfurization absorption tower 11. The measurement results measured by the SO ₂ concentration meters 32 a and 32 b and the flow meter 33 are transmitted to the control device 34. In addition, in the present Example, although the seawater circulation line L16 is provided, it is not limited to this and does not need to provide.

The control device 34 calculates the desulfurization rate in the flue gas desulfurization absorption tower 11 based on the inlet SO ₂ concentration and the outlet SO ₂ concentration of the exhaust gas 25 measured by the SO ₂ concentration meters 32a and 32b. The circulation flow rate of the sulfur-absorbing seawater 14 that circulates in the desulfurization absorption tower 11 is measured. The desulfurization rate of the exhaust gas 25 is adjusted by the ratio (exit SO ₂ concentration / inlet SO ₂ concentration) between the inlet SO ₂ concentration and the outlet SO ₂ concentration in the exhaust gas 25 supplied to the flue gas desulfurization absorption tower 11.

  The controller 34 supplies the absorption seawater 21a supplied to the flue gas desulfurization absorption tower 11 through the diluted seawater branch line L14 and the supply amount of the diluted seawater 21c supplied to the oxidation tank 12 and the exhaust gas through the air supply line L12. The supply amount of the air 29 supplied to the desulfurization absorption tower 11 is adjusted. Thus, the power required to supply the absorption seawater 21a and diluted seawater 21c with the pumps 22b and 22d into the flue gas desulfurization absorption tower 11, the air to the oxidation tank 12 with the blower 22e to the tower bottom 11a of the flue gas desulfurization absorption tower 11 The power to supply 29 can be reduced.

  Therefore, since the amount of dissolved oxygen in the sulfur-absorbing seawater 14 can be increased in the flue gas desulfurization absorption tower 11 by blowing air 29 into the bottom of the flue gas desulfurization absorption tower 11, the downstream oxidation tank 12. Therefore, the length of the oxidation tank 12 can be shortened and the size of the oxidation tank 12 can be reduced.

  Thus, the sulfur content absorption seawater 14 stored at the bottom of the flue gas desulfurization absorption tower 11 is fed to the oxidation tank 12 via the sulfur content absorption seawater discharge line L17.

Moreover, the sulfur content absorption seawater discharge line L17 may be connected to the diluted seawater supply line L14, and the sulfur content absorption seawater 14 in the sulfur content absorption seawater discharge line L17 may be mixed with the absorption seawater 21b and diluted. By mixing and diluting the sulfur-absorbing seawater 14 with the absorbing seawater 21b, the pH of the sulfur-absorbing seawater 14 in the sulfur-absorbing seawater discharge line L17 can be increased, and re-emission of SO ₂ gas can be prevented. Further, by preventing SO _{2 from} being diffused and leaking outside in the sulfur content absorption seawater discharge line L17, it is possible to prevent the emission of an irritating odor.

Moreover, you may make it provide the dilution mixing tank which dilutes and mixes the sulfur content absorption seawater 14 with the dilution seawater 21b in the sulfur content absorption seawater discharge line L17. By mixing and diluting the sulfur-absorbing seawater 14 with the absorbing seawater 21b, the pH of the sulfur-absorbing seawater 14 in the dilution mixing tank can be raised, and re-emission of SO ₂ gas can be prevented. Further, by preventing SO _{2 from} being diffused and leaking to the outside in the diluting / mixing tank, it is possible to prevent emitting an irritating odor.

  And the sulfur content absorption seawater 14 is supplied to the oxidation tank 12 provided in the downstream of the flue gas desulfurization absorption tower 11. FIG. The oxidation tank 12 is a tank that is provided on the downstream side of the flue gas desulfurization absorption tower 11 and performs a water quality recovery process for the sulfur-absorbing seawater 14. The oxidation tank 12 is a tank having an aeration apparatus (aeration apparatus) 41 that supplies air 29 to the sulfur content absorption diluted seawater 14 as air supply means.

The aeration apparatus 41 is provided in the oxidation tank 12 and supplies air 29 to the sulfur-absorbing seawater 14. In the present embodiment, the aeration apparatus 41 includes an oxidation air blower 42 that supplies air 29, an air diffuser 43 that supplies air 29, and an oxidation that supplies air 29 to the sulfur-absorbing seawater 14 in the oxidation tank 12. And an air nozzle 44. The external air 29 is sent from the oxidizing air nozzle 44 into the oxidation tank 12 through the air diffuser 43 by the oxidizing air blower 42, and the oxygen is dissolved as shown in the following formula (II). In the oxidation tank 12, the sulfur content in the sulfur-absorbing seawater 14 comes into contact with the air 29, and an oxidation reaction of bisulfite ions (HSO ₃ ⁻ ) as shown in the following formulas (III) to (V) and bicarbonate ions (HCO ₃ ^- produce and decarboxylation), sulfur absorbing seawater 14 is water recovered, the water recovery seawater 45. The number of the oxidizing air nozzles 44 is not particularly limited, and is appropriately provided according to the size of the inside of the oxidation tank 12.
O ₂ (g) → O ₂ (l) (II)
HSO ₃ ⁻ + 1 / 2O ₂ → SO ₄ ²⁻ + H ⁺ (III)
HCO ₃ ⁻ + H ⁺ → CO ₂ (g) + H ₂ O (IV)
CO ₃ ^2- + 2H ⁺ → CO ₂ (g) + H ₂ O (V)

As a result, the pH of the sulfur-absorbing seawater 14 can be raised and the COD can be reduced, and the pH, dissolved oxygen concentration, and COD of the water quality recovery seawater 45 can be released to a level at which seawater can be discharged. Moreover, even if gas is generated when the water quality of the sulfur-absorbing seawater 14 is recovered in the oxidation tank 12, the generated gas can be diffused in the oxidation tank 12 so as to satisfy the SO ₂ environmental standard concentration. The water quality recovery seawater 45 is discharged to the sea 22 via the seawater discharge line L18.

  The seawater flue gas desulfurization system 10 according to the present embodiment supplies the dilution seawater 21b and the air 29 to the absorption tower tank 11a of the flue gas desulfurization absorption tower 11, so that the sulfur content absorption seawater in the flue gas desulfurization absorption tower 11 is obtained. Since the amount of dissolved oxygen in 14 can be increased, the air blowing distance in the oxidation tank 12 can be reduced, and the length direction of the oxidation tank 12 can be shortened. Reduced.

  Table 1 shows an example of the relationship between the supply ratio of air and the supply ratio of diluted seawater and the length of the oxidation tank. In Table 1, the absorption tower bottom means the ratio of the supply amount of air 29 and diluted seawater 21c supplied to the tower bottom (absorption tower tank) 11a of the flue gas desulfurization absorption tower 11, and the oxidation tank The ratio of the supply amount of the air 29 supplied to the oxidation tank 12 and the diluted seawater 21b is shown.

  When supplying air 29 only to the oxidation tank 12 by supplying a part of the air 29 supplied to the oxidation tank 12 to the absorption tower tank 11a of the flue gas desulfurization absorption tower 11, as shown in Table 1. In comparison, the length of the oxidation tank 12 can be shortened (see Test Examples 1 to 8, and Comparative Examples 1 and 2).

  When a part of the air 29 supplied to the oxidation tank 12 is supplied to the tower bottom 11 a of the flue gas desulfurization absorption tower 11, the absorption tower tank 11 a of the flue gas desulfurization absorption tower 11 and the oxidation tank 12 are supplied. The length of the oxidation tank 12 can be shortened even if the supply amount of the air 29 is less than when supplying the air 29 only to the oxidation tank 12 (see Test Examples 4, 7, 8, and Comparative Examples 1 and 2). .

  Moreover, the diluted seawater 21c supplied to the absorption tower tank 11a of the flue gas desulfurization absorption tower 11 and the diluted seawater 21b supplied to the oxidation tank 12 are made equal to each other so as to be supplied to the tower bottom 11a of the flue gas desulfurization absorption tower 11. Even if the amount of air is reduced, the length of the oxidation tank 12 can be shortened to substantially the same extent as when air 29 is supplied in an equal amount to the bottom 11a of the flue gas desulfurization absorption tower 11 and the oxidation tank 12. The effect which reduces the magnitude | size of the oxidation tank 12 is acquired (refer Test Examples 1-6).

  Moreover, when the air 29 supplied to the absorption tower tank 11a of the flue gas desulfurization absorption tower 11 and the oxidation tank 12 is made equal, diluted seawater 21c supplied to the tower bottom 11a of the flue gas desulfurization absorption tower 11 and the oxidation tank Even if the total amount of the diluted seawater 21b supplied to 12 is reduced, the length of the oxidation tank 12 can be shortened compared to the case where the air 29 and the diluted seawater 21b are supplied only to the oxidation tank 12. (See Test Examples 5 and 6 and Comparative Example 1).

  Therefore, by supplying a part of the air 29 supplied to the oxidation tank 12 to the absorption tower tank 11a of the flue gas desulfurization absorption tower 11 in advance, the sulfur content absorption seawater 14 in the flue gas desulfurization absorption tower 11 is supplied. The amount of dissolved oxygen can be increased. Thereby, since the blowing distance of the air 29 in the oxidation tank 12 can be reduced and the length direction of the oxidation tank 12 can be shortened, the size of the oxidation tank 12 can be reduced.

  As described above, the seawater flue gas desulfurization system 10 according to the present embodiment supplies a part of the air 29 supplied to the oxidation tank 12 to the bottom of the flue gas desulfurization absorption tower 11 and the oxidation tank 12. By supplying a part of the seawater 21b for dilution supplied to the bottom of the flue gas desulfurization absorption tower 11, it is possible to reduce the air blowing distance in the oxidation tank 12, and the length direction of the oxidation tank 12 is changed. Since it can be shortened, the size of the oxidation tank 12 can be reduced. Further, since the power required to supply the air 29 to the oxidation tank 12 can be reduced, the sulfur-absorbing seawater 14 that has flowed into the open-open oxidation tank 12 can be efficiently oxidized to recover the water quality. it can.

  Therefore, according to the seawater flue gas desulfurization system 10 according to the present embodiment, the sulfur content absorption seawater 14 discharged from the flue gas desulfurization absorption tower 11 is efficiently treated in the oxidation tank 12 by treating the sulfur content absorption seawater 14 with water quality. A recovery process can be performed to reduce the size of the oxidation tank 12, and a highly reliable seawater flue gas desulfurization system can be provided.

  Moreover, in the present Example, although the seawater flue gas desulfurization system which processes the absorption seawater 21a used for seawater desulfurization with the flue gas desulfurization absorption tower 11 was demonstrated, this invention is not limited to this. Seawater flue gas desulfurization equipment is included in exhaust gas discharged from factories in various industries, power plants such as large and medium-sized thermal power plants, large boilers for electric utilities or general industrial boilers, steelworks, smelters, etc. The present invention can also be applied to a seawater flue gas desulfurization apparatus that desulfurizes sulfur oxides.

  In the present embodiment, the flue gas desulfurization absorption tower 11 and the oxidation tank 12 are independent as separate tanks, and the flue gas desulfurization absorption tower 11 and the oxidation tank 12 are connected by a sulfur content absorption seawater discharge line L17. However, the present embodiment is not limited to this, and the flue gas desulfurization absorption tower 11 and the oxidation tank 12 may be integrated into a single tank.

  A power generation system according to Embodiment 2 of the present invention will be described with reference to the drawings. The seawater flue gas desulfurization system according to the first embodiment is used for the seawater flue gas desulfurization system applied to the power generation system according to the present embodiment. In addition, about the member similar to Example 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

FIG. 2 is a schematic diagram illustrating a configuration of a power generation system according to Embodiment 2 of the present invention. As shown in FIG. 2, the power generation system 50 according to this embodiment includes a boiler 51, a steam turbine 52, a condenser 53, a flue gas denitration device 54, a dust collector 55, and a seawater flue gas desulfurization system. 10. In the present embodiment, as described above, the sulfur-absorbing seawater 14 is used seawater that has absorbed sulfur such as SO ₂ in the seawater flue gas desulfurization system 10.

  The boiler 51 injects and burns fuel 56 supplied from an oil tank or a coal mill from a burner (not shown) together with air 58 preheated by an air preheater (AH) 57. The air 58 supplied from the outside is supplied to the air preheater 57 by the pushing fan 59 and preheated. The fuel 56 and the air 58 preheated by the air preheater 57 are supplied to the burner, and the fuel 56 is combusted in the boiler 51. Thereby, the steam 60 for driving the steam turbine 52 is generated.

  Exhaust gas 61 generated by combustion in the boiler 51 is fed to the flue gas denitration device 54. Further, the exhaust gas 61 is used as a heat source for exchanging heat with water 62 discharged from the condenser 53 and generating steam 60. The steam turbine 52 uses this generated steam 60 to drive the generator 63. The condenser 53 collects the water 62 condensed by the steam turbine 52 and returns it to the boiler 51 for circulation.

  The exhaust gas 61 discharged from the boiler 51 is denitrated in the flue gas denitration device 54, exchanges heat with the air 58 by the air preheater 57, and then sent to the dust collector 55 to remove the dust in the exhaust gas 61. The exhaust gas 61 removed by the dust collector 55 is supplied into the flue gas desulfurization absorption tower 11 by the induction fan 65. At this time, the exhaust gas 61 is heat-exchanged by the heat exchanger 66 with the purified gas 28 that is desulfurized and discharged by the flue gas desulfurization absorption tower 11, and then supplied into the flue gas desulfurization absorption tower 11. Further, the exhaust gas 61 may be directly supplied to the flue gas desulfurization absorption tower 11 without exchanging heat with the purified gas 28 by the heat exchanger 66.

  The heat exchanger 66 includes a heat recovery device and a reheater, and a heat medium circulates between the heat recovery device and the reheater. The heat recovery unit is provided between the induction fan 65 and the flue gas desulfurization absorption tower 11, and exchanges heat between the exhaust gas 61 discharged from the boiler 51 and the heat medium. The reheater is provided on the downstream side of the flue gas desulfurization absorption tower 11, exchanges heat between the purified gas discharged from the flue gas desulfurization absorption tower 11 and the heat medium, and reheats the purified gas. To do.

  The seawater flue gas desulfurization system 10 is the seawater flue gas desulfurization apparatus according to the first embodiment. That is, the seawater flue gas desulfurization system 10 includes a flue gas desulfurization absorption tower 11, an oxidation tank 12, a seawater supply line L11, and an air branch line L12.

  In the seawater flue gas desulfurization system 10, as described above, seawater desulfurization is performed using the seawater 21 pumped up from the sea 22 by the sulfur content contained in the exhaust gas 61. Further, the seawater 21 is pumped up from the sea 22 by the pump 22a, and after heat exchange is performed by the condenser 53, a part of the seawater 21a is sent to the seawater flue gas desulfurization system 10 by the pump 22b through the seawater supply line L11. The Moreover, the diluted seawater 21b is supplied to the upstream side in the oxidation tank 12 through the diluted seawater supply line L13. In the flue gas desulfurization absorption tower 11, the exhaust gas 61 and the absorbed seawater 21a are brought into gas-liquid contact, and the sulfur content in the exhaust gas 61 is absorbed by the absorption seawater 21a. The exhaust gas 61 purified by the seawater flue gas desulfurization system 10 becomes the purified gas 28 and is discharged to the outside from the chimney 67 through the purified gas discharge passage L15.

  Further, diluted seawater 21 c and air 29 are supplied to the tower bottom 11 a of the flue gas desulfurization absorption tower 11. Therefore, since the amount of dissolved oxygen in the sulfur-absorbing seawater 14 can be increased in the flue gas desulfurization absorption tower 11, it becomes possible to reduce the air blowing distance in the oxidation tank 12, as will be described later. Therefore, the size of the oxidation tank 12 can be reduced.

  The sulfur-absorbing seawater 14 that has absorbed the sulfur is discharged from the flue gas desulfurization absorption tower 11 and then fed to the upstream side of the oxidation tank 12. It is mixed with the absorption seawater 21b on the upstream side in the oxidation tank 12 and diluted.

  The seawater 21 pumped from the sea 22 is heat-exchanged by the condenser 53 and then sent to the seawater flue gas desulfurization system 10 and used for seawater desulfurization. The seawater 21 pumped from the sea 22 is condensed into the condensate. It is also possible to directly feed the seawater flue gas desulfurization system 10 without heat exchange in the vessel 53 and use it for seawater desulfurization.

  The sulfur-absorbing seawater 14 is mixed with the absorbing seawater 21b on the upstream side of the oxidation tank 12, and then oxidized. In the present embodiment, as described above, the diluted seawater 21c and the air 29 are supplied to the bottom of the smoke desulfurization absorption tower 11, and the amount of dissolved oxygen in the sulfur content absorption seawater 14 is increased in the flue gas desulfurization absorption tower 11. Therefore, the air blowing distance in the oxidation tank 12 can be reduced, and the length direction of the oxidation tank 12 can be shortened, so that the size of the oxidation tank 12 can be reduced. Further, since the total amount of air supplied into the oxidation tank 12 can be reduced in the oxidation tank 12, the power required to supply the air 29 to the oxidation tank 12 can be reduced, and the open-type The sulfur-absorbing seawater 14 that has flowed into the oxidation tank 12 can be efficiently oxidized to recover the water quality.

  In this way, the water quality of the sulfur-absorbing seawater 14 is recovered in the oxidation tank 12 to obtain the water quality recovered seawater 45. The water quality recovery seawater 45 obtained in the oxidation tank 12 is discharged from the oxidation tank 12 to the sea 22 via the seawater discharge line L18 with pH, dissolved oxygen concentration, and COD at a level at which seawater can be discharged.

  Further, a part of the seawater 21 may be supplied from the seawater supply line L11 to the downstream side of the water quality recovery seawater 45 in the oxidation tank 12 through the diluted seawater supply line L19. Thereby, the water quality recovery seawater 45 can be further diluted. As a result, the pH of the water quality recovery seawater 45 is increased, the pH of the seawater drainage is increased to near the seawater, the drainage standard for the pH of the seawater drainage (pH 6.0 or more) is satisfied, and COD is reduced. It is possible to release the pH and COD of the water quality recovery seawater 45 as a level at which seawater can be discharged.

  Thus, according to the power generation system 50 according to the present embodiment, by supplying the air 29 to the bottom of the flue gas desulfurization absorption tower 11, the sulfur-absorbing seawater 14 discharged from the flue gas desulfurization absorption tower 11. In the oxidation tank 12, the sulfur-absorbing seawater 14 can be efficiently processed, the air blowing distance in the oxidation tank 12 can be reduced, and the size of the oxidation tank 12 can be reduced. Moreover, the motive power which supplies the air 29 to the sulfur content absorption seawater 14 in the oxidation tank 12 can be reduced, and the running cost can be suppressed. Therefore, the power generation system 50 according to the present embodiment can efficiently and stably process the sulfur-absorbing seawater 14 and perform water quality recovery processing, and can provide a power generation system with high safety and reliability. .

  Further, the seawater flue gas desulfurization system 10 according to the present embodiment is included in exhaust gas discharged from factories in various industries, power plants such as large-sized and medium-sized thermal power plants, large boilers for electric utilities, or general industrial boilers. It can be used for removal of sulfur content in the sulfur content absorption solution produced by desulfurizing the sulfur oxide.

DESCRIPTION OF SYMBOLS 10 Seawater flue gas desulfurization system 11 Flue gas desulfurization absorption tower 11a Absorption tower tank 12 Oxidation tank 14 Sulfur content absorption seawater 21 Seawater 22 Sea 21a Absorption seawater 21b, 21c Diluted seawater 22a-22d Pump 22e Blower 25, 61 Exhaust gas 26 Spray nozzle 28 Purified gas 29 Air 32a, 32b SO ₂ concentration meter 33 Flow meter 34 Control device 41 Aeration device (aeration device)
42 Oxidizing air blower 43 Aeration pipe 44 Oxidizing air nozzle 45 Water quality recovery seawater 50 Power generation system 51 Boiler 52 Steam turbine 53 Condenser 54 Flue gas denitration device 55 Dust collector 56 Fuel 57 Air preheater (AH)
58 Air 59 Push-in fan 60 Steam 62 Water 63 Generator 65 Induction fan 66 Heat exchanger 67 Chimney L11 Seawater supply line L12 Air branch line L13, L14, L19 Diluted seawater supply line L15 Purified gas discharge passage L16 Seawater circulation line L17 Sulfur content Absorption seawater discharge line L18 Seawater discharge line

Claims (7)

A flue gas desulfurization absorption tower that cleans the exhaust gas by gas-liquid contact between the exhaust gas and seawater;
An oxidation tank that is provided on the downstream side of the flue gas desulfurization absorption tower and includes air supply means for supplying air to sulfur-absorbing seawater containing sulfur, and performs water quality recovery processing of the sulfur-absorbing seawater;
A seawater supply line for supplying the seawater to the flue gas desulfurization absorption tower;
An air branch line for supplying a part of the air supplied to the oxidation tank to the bottom of the flue gas desulfurization absorption tower,
A seawater flue gas desulfurization system characterized by comprising: In claim 1,
A seawater flue gas desulfurization system comprising a dilute seawater branch line that branches from the seawater supply line and supplies a portion of the seawater as diluted seawater to the bottom of the flue gas desulfurization absorption tower. In claim 1 or 2,
The seawater flue gas desulfurization system, wherein the SO ₂ absorption amount relative to the total amount of the seawater supplied to the flue gas desulfurization absorption tower is 3 mmol / l or less. In any one of Claims 1-3,
The seawater flue gas desulfurization system, wherein the temperature of the sulfur-absorbing seawater is 5 ° C or higher and 55 ° C or lower. In any one of Claims 1-4,
The seawater flue gas desulfurization system, wherein the seawater has a pH of 5.5 or more. In any one of claims 1 to 5,
An SO ₂ concentration meter for measuring an inlet SO ₂ concentration and an outlet SO ₂ concentration of the exhaust gas at an inlet and an outlet of the exhaust gas of the flue gas desulfurization absorption tower;
A seawater circulation line for circulating the sulfur-absorbing seawater in the flue gas desulfurization absorption tower to the seawater supply line;
A flow meter that is provided in the seawater circulation line and measures the flow rate of the sulfur-absorbing seawater extracted from the flue gas desulfurization absorption tower;
Have
Calculate the desulfurization rate in the flue gas desulfurization absorption tower based on the inlet SO ₂ concentration and outlet SO ₂ concentration of the exhaust gas,
A seawater flue gas desulfurization system characterized by adjusting a supply amount of seawater supplied to the oxidation tank via the diluted seawater branch line. With a boiler,
Using the exhaust gas discharged from the boiler as a heat source for steam generation, and a steam turbine for driving a generator using the generated steam;
A seawater flue gas desulfurization system according to any one of claims 1 to 6;
A condenser for collecting and circulating the water condensed in the steam turbine;
A flue gas denitration device for denitrating exhaust gas discharged from the boiler;
A dust collector for removing the dust in the exhaust gas;
A power generation system comprising:

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