JP2004337776A - Exhaust gas treating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust gas treating apparatus removing sulfur in the gas efficiently and improving the efficiency of utilization of the sulfur removed. <P>SOLUTION: The apparatus has a flue-gas desulfurization unit 102 removing sulfur oxides in an exhaust gas 101 emitted from e.g. a boiler 100, a cleaning tower 104 arranged downstream to the unit 102 and causing a cleaned exhaust gas 103 discharged from the unit 102 to pass through, a catalyst layer 107 disposed within the tower 104 and composed of an active active carbon fiber layer oxidizing residual sulfur oxides with supplied water 105 to form diluted sulfuric acid 106, a means 108 of supplying the acid 106 thus produced to the unit 102 and a stack 110 emitting a cleaned gas 109 cleaned in the tower. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an exhaust gas treatment device for removing sulfur oxides (SOx) in exhaust gas discharged from boilers, gas turbines, engines, incinerators, and the like that burn fuel such as coal and heavy oil.
[0002]
[Background Art]
BACKGROUND ART Conventionally, as a method for removing sulfur oxides in exhaust gas, a lime-gypsum method in which limestone or slaked lime slurry is used as an absorbent and the sulfur content in the exhaust gas is collected as gypsum has been adopted. As another method, a dry method of adsorption with activated carbon is known.
[0003]
In the above-mentioned conventional lime-gypsum method, limestone or slaked lime slurry is sprayed into exhaust gas to simultaneously perform humidifying cooling of the exhaust gas and absorption of SOx.
[0004]
FIG. 7 shows an example of the conventional lime-gypsum method.
As shown in FIG. 7, an exhaust gas 11 from a boiler or the like is introduced, and an absorber 13 (eg, a lime slurry) containing a calcium compound is used to contact the exhaust gas 11 containing a sulfur component with a filler 13a. A liquid storage chamber 15 for storing the slurry 14 after contact with the exhaust gas 11, an oxidation tower 17 for extracting the slurry 14 in the liquid storage chamber 15 with a pump 16 and supplying an oxygen-containing gas (air or the like); A circulation pump 18 for extracting the slurry 14 from the storage chamber 15 and supplying the slurry 14 to the inside of the absorption tower 13, a sedimentation tank (thickener) 20 for sedimenting the gypsum slurry 19 from the oxidation tower 17, And a dehydrator 23 for removing gypsum as wastewater (filtrate) 21 to obtain gypsum 22.
[0005]
According to the desulfurization apparatus, the exhaust gas is purified by removing the sulfur component from the exhaust gas containing the sulfur component, and at the same time, gypsum is manufactured as a by-product (Patent Documents 1 and 2). .
[0006]
Here, the following “reaction I” occurs in the liquid storage chamber 15 and the following “reaction II” occurs in the oxidation tower 17. However, in the conventional method, in order to improve the productivity, the oxidation tower 17 is formed. The pH was controlled by adding commercially available sulfuric acid.
[Reaction I]
SO₂+ CaCO₃+ (1/2) H₂O → CaSO₃・ (1/2) H₂O + CO₂
[Reaction II]
CaSO₃・ (1/2) H₂O + (1/2) O₂+ (3/2) H₂O → CaSO₄・ 2H₂O
[0007]
[Patent Document 1]
JP-A-9-10547
[Patent Document 2]
JP-A-9-253443
[0008]
[Problems to be solved by the invention]
However, there is a problem that gypsum in the oxidation tower 17 by the lime-gypsum method described above includes calcium sulfite as a by-product. Conventionally, oxygen was supplied to improve the quality of gypsum, but further improvement in quality is desired.
[0009]
In view of the above problems, an object of the present invention is to provide an exhaust gas treatment device that efficiently removes a sulfur component in exhaust gas and improves the utilization efficiency of desulfurized sulfur.
[0010]
[Means for Solving the Problems]
A first invention for solving the above-mentioned problem is a flue gas desulfurization device for removing sulfur oxides in exhaust gas, and a purified gas provided on the downstream side of the flue gas desulfurization device and discharged from the flue gas desulfurization device. A purification tower provided in the purification tower, a catalyst layer formed of an activated carbon fiber layer, a water supply means for supplying water for sulfuric acid generation to the catalyst layer, and the generated diluted sulfuric acid. An exhaust gas treatment apparatus comprising: a sulfuric acid supply unit that supplies the sulfur dioxide to the flue gas desulfurization apparatus.
[0011]
The second invention uses an slurry containing a calcium compound, an absorption tower that is brought into contact with an exhaust gas containing a sulfur component, a liquid storage chamber that stores the slurry after contact with the exhaust gas, and an oxidizing unit that supplies an oxygen-containing gas to the slurry. A circulation pump for extracting slurry from the liquid storage chamber and supplying the slurry to the inside of the absorption tower, a purification tower for flowing a purification gas discharged from the absorption tower, and a purification tower provided in the purification tower; An exhaust gas treatment comprising: a catalyst layer to be formed; a water supply means for supplying water for producing sulfuric acid to the catalyst layer; and a sulfuric acid supply means for supplying the produced diluted sulfuric acid to the oxidizing means. In the device.
[0012]
A third invention is the flue gas desulfurization device according to the first invention, wherein the absorption tower and the purification tower are integrated.
[0013]
The fourth invention uses an slurry containing a calcium compound, and an absorption tower for contacting an exhaust gas containing a sulfur component through a filling tank, a liquid storage chamber for storing the slurry after contact with the exhaust gas, and an oxygen-containing gas to the slurry. Oxidizing means for supplying, a circulation pump for extracting the slurry from the liquid storage chamber and supplying the slurry to the inside of the absorption tower, and activated carbon fibers provided on the downstream side of the filling tank in the absorption tower for flowing the purified gas An exhaust gas treatment apparatus comprising: a catalyst layer formed of a layer; and a water supply unit that supplies water for producing sulfuric acid to the catalyst layer.
[0014]
According to a fifth aspect of the present invention, there is provided the exhaust gas treatment apparatus according to any one of the first to fourth aspects, wherein a mist particle diameter in the exhaust gas cooled and humidified is 50 to 150 μm.
[0015]
According to a sixth aspect of the present invention, in any one of the first to fifth aspects, an inlet for exhaust gas containing sulfur oxide is provided at a lower portion of the purification tower, and an outlet for the exhaust gas is provided at an upper portion. An exhaust gas treatment device is provided with a humidification cooling device that humidifies and cools exhaust gas supplied into the purification tower.
[0016]
A seventh invention is the exhaust gas treatment device according to the sixth invention, wherein the humidification cooling device is provided in a stage preceding the purification tower.
[0017]
An eighth invention is the exhaust gas treatment device according to the sixth invention, wherein the humidification cooling device is provided at a stage preceding the catalyst layer in the purification tower.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the exhaust gas treatment apparatus according to the present invention will be described below, but the present invention is not limited to these embodiments.
[0019]
[First Embodiment]
The exhaust gas treatment apparatus according to the present embodiment is provided with a flue gas desulfurization apparatus 102 for removing sulfur oxides in the exhaust gas 101 discharged from the boiler 100 and the like, and is provided on the downstream side of the flue gas desulfurization apparatus 102. A purifying tower 104 through which the purified exhaust gas 103 discharged from the smoke desulfurization apparatus 102 flows, and an activity for oxidizing residual sulfur oxides with water 105 provided in the purifying tower 104 and producing diluted sulfuric acid 106. A catalyst layer 107 formed of a carbon fiber layer, a sulfuric acid supply means 108 for supplying the generated diluted sulfuric acid 106 to the flue gas desulfurization device 102, and a chimney 110 for discharging a purified gas 109 purified by the purification tower 104. Is provided.
[0020]
In the flue gas desulfurization device 102, generally, the sulfur oxide concentration in the exhaust gas 101 can be reduced to about one tenth thereof, but the sulfur oxide concentration may still remain. In the present invention, the sulfur oxide is further purified by the purification tower 104 having the catalyst layer 107 provided on the downstream side of the flue gas desulfurization device 102.
[0021]
As a result, the purified gas has almost no sulfur oxides. During this desulfurization, the catalyst layer 107 produces dilute sulfuric acid 106 from sulfur oxides in the exhaust gas due to its strong oxidizing power (described later in detail). In the present invention, the dilute sulfuric acid 106 thus obtained is returned to the flue gas desulfurization device 102 so as to be effectively used.
[0022]
For example, in the case of a desulfurization facility using the lime-gypsum method, the diluted sulfuric acid 106 is used as an oxidation aid for adjusting the oxidation conditions for gypsum formation.
[0023]
Here, examples of the flue gas desulfurization apparatus include, in addition to the desulfurization equipment using the lime-gypsum method, desulfurization equipment using the dilute limestone-gypsum method, desulfurization equipment using the soda-limestone method, desulfurization equipment using the Wellman road method, and the like. In each facility, sulfuric acid is used efficiently.
[0024]
For example, in a desulfurization facility using a dilute sulfate limestone-gypsum method, sulfuric acid can be used to increase the amount of sulfuric acid in the main engine as shown below.
H₂SO₄+ CaCO₃→ CaSO₄+ H₂O + CO₂
[0025]
Further, in a desulfurization facility using the soda-limestone method, as shown below, CaSO₃Can be changed.
CaSO₃+ H₂SO₄→ CaSO₄+ SO₂+ H₂O
[0026]
Further, in a desulfurization facility based on the Wellman Road method, as shown below,₂SO₃Can be dissolved.
Na₂SO₃+ H₂SO₄→ Na₂SO₄+ SO₂+ H₂O
[0027]
Hereinafter, the contents of the present invention will be described in detail using a flue gas desulfurization apparatus using a desulfurization facility of the lime-gypsum method.
[0028]
FIG. 2 schematically shows an exhaust gas treatment apparatus according to the present embodiment.
As shown in FIG. 2, the exhaust gas treatment apparatus according to the present embodiment is obtained by introducing exhaust gas 101 from a boiler 100 or the like, uses an absorbent (eg, gypsum slurry) 12 containing a calcium compound, and contains a sulfur component. An absorption tower 13 for bringing the exhaust gas 101 into contact with the filler 13a, a liquid storage chamber 15 for storing the slurry 14 after contact with the exhaust gas 101, and the slurry 14 in the liquid storage chamber 15 is withdrawn by a pump 16 to supply an oxygen-containing gas. An oxidation tower 17, a circulating pump 18 for extracting the slurry 14 from the liquid storage chamber 15, and supplying the slurry 14 from above the filler 13 a in the absorption tower 13 through a water spray nozzle 25, A sedimentation tank (thickener) 20 for sedimenting the gypsum slurry 19 from the gypsum, and water is removed from the gypsum slurry 19 as wastewater (filtrate) 21 to remove the gypsum. A dewatering device 23 for obtaining the exhaust gas 22; a purification tower 104 through which the purified exhaust gas 103 discharged from the absorption tower 13 flows; a catalyst layer 107 provided in the purification tower 104 and formed of an activated carbon fiber layer; The layer 107 includes a water supply unit 111 for supplying water 105 for producing sulfuric acid to the layer 107, and a liquid supply pump 108 serving as a sulfuric acid supply unit for supplying the diluted sulfuric acid 106 to the oxidizing unit 17.
[0029]
In the exhaust gas treatment apparatus having the above configuration, as shown in FIG. 2, sulfur oxides in the exhaust gas 101 are adsorbed by the lime slurry 14 by the adsorption tower 13 which is a flue gas desulfurization apparatus (reaction I), and the oxidation tower 17 is used. After the gypsum slurry 19 is obtained in (2) (reaction II), the gypsum slurry 19 is subjected to dehydration treatment and used as gypsum 22. At this time, sulfur oxides slightly remaining in the purified exhaust gas 103 purified by the adsorption tower 13 are further purified by the purification tower 104 so as to be a purified gas 109 having almost no sulfur oxides. In this purification tower 104, the diluted sulfuric acid produced is used for adjusting the pH of the oxidation conditions in the reaction II in the oxidation tower 14 of the slurry 14 from the flue gas desulfurization unit. This allows CaSO₃・ (1/2) H₂A high-grade gypsum containing no O can be obtained.
[0030]
[Reaction I]
SO₂+ CaCO₃+ (1/2) H₂O → CaSO₃・ (1/2) H₂O + CO₂
[Reaction II]
CaSO₃・ (1/2) H₂O + (1/2) O₂+ (3/2) H₂O → CaSO₄・ 2H₂O
[0031]
Here, a method for desulfurizing a trace amount of sulfur oxides in the purified exhaust gas 103 will be described with reference to FIG.
In the present embodiment, the purified exhaust gas 103 once desulfurized in the absorption tower 13 is introduced into the purification tower 104 from the inlet on the lower side wall by the pushing fan 121. Inside the purification tower 104, there is provided a catalyst layer 107 formed of an activated carbon fiber layer. In the catalyst layer 107, water 105 for producing sulfuric acid is supplied from a water supply means 111 comprising a water tank 111a and a supply pump 111b. Supplied. Water 105 from the supply means 111 is supplied from above, and the purified exhaust gas 103 is passed through the inside of the catalyst layer 107 from below, thereby reacting and removing SOx from the purified exhaust gas 103. The purified gas 109 that has passed through the catalyst layer 107 is discharged from a discharge section above the purification tower 104, and is discharged to the atmosphere through a chimney.
[0032]
The catalyst layer 107 includes a catalyst composed of a plurality of activated carbon fiber layers. On the surface of each activated carbon fiber layer, for example, a desulfurization reaction occurs by the following reaction.
That is,
(1) Sulfur dioxide SO in exhaust gas to the activated carbon fiber layer of the catalyst₂Adsorption.
(2) SO2 adsorbed₂And oxygen O in exhaust gas₂(Can be supplied separately) with sulfur trioxide SO₃Oxidation to.
(3) oxidized sulfur trioxide SO₃Water H₂Sulfuric acid H by dissolution in O₂SO₄Generation. (4) Sulfuric acid H generated₂SO₄From the activated carbon fiber layer.
[0033]
The reaction formula at this time is as follows.
SO₂+ 1 / 2O₂+ H2O → H₂SO₄
[0034]
Sulfuric acid H removed by the above reaction₂SO₄Is turned into diluted sulfuric acid and supplied to the oxidation tower 17 which is a gypsum reaction tank via the liquid sending pump 108 (see FIG. 1).
Thus, in the activated carbon fiber layer of the catalyst layer 107, the sulfur dioxide (SO₂) Is adsorbed and oxidized, and water (H₂O) to react with sulfuric acid (H₂SO₄) Is generated and desorbed and removed, thereby performing desulfurization in exhaust gas.
[0035]
Here, an example of an activated carbon fiber used in the catalyst layer 107 of the present invention and an example of a production example thereof are shown below.
Examples of the activated carbon fibers used in the present invention include pitch-based activated carbon fibers, polyacrylonitrile-based activated carbon fibers, phenol-based activated carbon fibers, and cellulose-based activated carbon fibers, but the present invention is not limited thereto. The activated carbon fibers exhibiting the above-mentioned catalytic action are not limited at all.
[0036]
Specific production examples are shown below.
(Production Example 1)
Phenol-based activated carbon fiber ("Cractive-20", manufactured by Kuraray Chemical Co., Ltd.) is used and calcined in a nitrogen atmosphere at a temperature in the range of 900 to 1200C for 1 hour.
[0037]
(Production Example 2)
A polyacrylonitrile-based activated carbon fiber (“FX-600”, manufactured by Toho Rayon Co., Ltd.) is used and fired in a nitrogen atmosphere at a temperature range of 900 to 1200 ° C. for 1 hour.
[0038]
FIG. 3 is a schematic diagram of the purification tower 104 according to the present embodiment, and FIG. 4 is a perspective view of the activated carbon fiber layer.
As shown in FIG. 3, the purification tower 104 has an inlet for the exhaust gas 103 containing sulfur oxide on a side wall of the purification tower, an outlet 12 for the exhaust gas 100 at an upper portion, and the purification tower 104. A sprinkling nozzle 122, which is a water supply device for producing sulfuric acid, is provided above a catalyst layer 107 formed of an activated carbon fiber layer provided therein, and the supplied purified exhaust gas 103 is provided below the purification tower. A rectifying plate 124 having a rectifying dispersion hole 123 is provided.
[0039]
As shown in FIG. 4, the activated carbon fiber layer 125 that forms one unit of the catalyst layer 107 has a flat activated carbon fiber sheet 126 having a flat shape and a corrugated activated carbon fiber sheet 127 having a corrugated shape alternately laminated. , A linear space formed therebetween becomes a passage 128, and the passage 128 extends vertically.
The flat plate activated carbon fiber sheet 126 and the corrugated plate activated carbon fiber sheet 127 are plate-shaped, and the corrugated plate activated carbon fiber sheet 127 is further formed into a corrugated shape using, for example, a corrugator.
Further, in addition to the corrugated sheet shape, for example, the exhaust gas may be formed into a shape such as a honeycomb shape that allows exhaust gas to pass in parallel with the activated carbon fiber sheet.
[0040]
Then, as shown in FIG. 3, water is supplied in a spray form from the watering nozzle 122 and the purified exhaust gas 103 is sent from below, and the water 105 flowing through the activated carbon fiber layer 125 has a particle size of about several mm. And fall to the bottom.
Since the purified exhaust gas 103 flows through the passage 128 formed by alternately stacking the flat activated carbon fiber sheets 126 and the corrugated activated carbon fiber sheets 127, an increase in pressure loss is suppressed. I have.
[0041]
In order to dispose the catalyst layer in the desulfurization tower, first, an activated carbon fiber layer 125 laminated in a frame (not shown) is filled to form a catalyst layer (for example, having a height of 0.5 m to 4 m). The catalyst layer is provided in the purification tower 104 by, for example, lifting means.
[0042]
Here, the amount of water (water / humidified exhaust gas) when the purified exhaust gas 103 comes into contact with the catalyst layer in the purification tower 104 according to the present embodiment is a saturated water vapor amount + 0.5 to 10, preferably a saturated water vapor. It is preferable to set the amount of water vapor +1.0 to 1.5% by volume. The amount of the saturated steam is, for example, 12.2% by volume (50 ° C.) at 50 ° C. The saturated steam amount at 40 ° C. is 7.3% by volume, and the saturated steam amount at 60 ° C. is 19.7% by volume. This is because the desulfurization of sulfuric acid in the desulfurization action as described above is not performed well below the saturation amount. For this reason, as shown in FIG. 3, by using the humidifying cooling device 116 that supplies the humidifying cooling water 115 to the purified exhaust gas 103 before being supplied to the purification tower 104, the saturated steam amount can be increased to a certain level or more. I have.
[0043]
Further, the cooling temperature of the humidification cooling may be appropriately determined according to the relationship between the temperature of the exhaust gas and the amount of moisture, and is preferably, for example, 40 to 60 ° C. This is because, when the temperature exceeds 60 ° C., the evaporation amount of water increases, the water supply amount increases, and the processing cost increases. On the other hand, when the temperature is lower than 40 ° C., the temperature cannot be substantially lowered by the humidifying cooling of general exhaust gas.
[0044]
That is, when the purified exhaust gas 103 is supplied into the purification tower 104 in a state where the moisture is saturated by the humidifying cooling of the humidifying cooling device 116 and comes into contact with the catalyst layer 107, the exhaust gas moisture amount is reduced to the saturated steam amount. +0.5 to 10 (preferably, the saturated water vapor amount +1.0 to 1.5% by volume), so that the SO on the catalyst surface₂Produced by the oxidation of₃Will rapidly proceed. As a result, since sulfuric acid does not remain on the surface of the activated carbon fiber, active points are effectively used and desulfurization efficiency is improved.
[0045]
Here, in FIG. 3, the purified exhaust gas 103 is supplied from the lower side of the tower. In this case, since the mist as moisture may stay at the lower part of the tower, the exhaust gas moisture content is increased by the saturated steam amount +0.5. It is necessary to slightly increase the amount of water from the water spray nozzle 122 so as to be 10 to 10 (preferably the amount of saturated steam + 1.0 to 1.5% by volume).
[0046]
On the other hand, unlike the apparatus configuration shown in FIG. 3, when the purified exhaust gas 103 is lowered from above the tower, mist is also supplied to the catalyst layer 107, so that the amount of water spray is reduced as compared with the case shown in FIG. Sometimes you can.
In any case, it is important that the exhaust gas is higher than the saturated vapor. In particular, by setting the saturated vapor amount +1.0 to 1.5% by volume, the activity of the catalyst as an extremely efficient water supply can be increased. It can be applied to the surface of carbon fiber.
That is, only the amount of the saturated water vapor can be used to determine SO 2₂  Oxidized SO₃  Is insufficient to be desorbed as sulfuric acid due to moisture, and if it exceeds the saturated vapor amount + 1.5% by volume, the amount of water becomes excessive, and the diluted sulfuric acid is further diluted. Increase and become less desirable. Furthermore, when the water content is large, the active points on the surface of the activated carbon fiber are covered, so that the function as a catalyst cannot function, and as a result, the desulfurization efficiency is reduced.
[0047]
The relationship between saturated steam and steam mist is not clear, but SO₂Oxidized SO₃Is discharged as sulfuric acid due to moisture, if the water is insufficient, it cannot be discharged as sulfuric acid, and the next SO₂Is insufficiently oxidized. On the other hand, if the water content is excessive, the sulfuric acid will be diluted. Further, when the water content becomes excessive, for example, when a water film or a water wall is formed on the surface of the activated carbon fiber, the active point of the activated carbon fiber is covered,₂Cannot catalyze the oxidation of sulfur, and cannot be desulfurized, resulting in reduced desulfurization efficiency.
Therefore, as in the present invention, when the amount of water (moisture / humidified exhaust gas) when the exhaust gas contacts the catalyst layer is set to the saturated water vapor amount +1.0 to 1.5% by volume, the water droplets are intermittently ball-shaped. As a result, water is supplied to the surface of the activated carbon fiber without excess and deficiency, and sulfuric acid is efficiently desorbed. As a result, desulfurization of exhaust gas is effectively performed.
[0048]
It is preferable that the particle size of the cooling water supplied from the water spray nozzle 122 serving as the water supply means is 300 to 1000 μm. This is because, when the amount exceeds the above range, effective water supply on the surface of the activated carbon fiber cannot be performed, and the desorbing action of sulfuric acid does not proceed well, which is not preferable. In particular, when the exhaust gas is supplied from the lower side, the mist-like water from the water spray nozzle 122 rises, and good water supply cannot be performed. On the other hand, if the water particle size is too large, a water wall state is formed, and although sulfuric acid can be desorbed, the active sites do not surface and the desulfurization reaction does not proceed, which is not preferable.
[0049]
For this purpose, the supply amount of the water 105 supplied from the water supply means 111 is preferably 5 to 50 ml / m, when the flow rate of the purified exhaust gas 103 into the purification tower is 0.5 to 5 m / s.³  It is good to use exhaust gas.
[0050]
Further, it is preferable that the mist particle diameter in the exhaust gas subjected to the humidification cooling by the humidification cooling device 116 is 50 to 150 μm. This is because, when the diameter is less than 50 μm, the water in the exhaust gas evaporates immediately before introduction into the desulfurization tower, which is not preferable. On the other hand, when the diameter exceeds 150 μm, the water adheres to the pipe, which is preferable. Because there is no.
[0051]
Here, a mist catcher (not shown) for supplying the mist may be provided. By providing this catcher, the introduction of moisture into the desulfurization tower can be suppressed, and sulfuric acid generated by desulfurization in the catalyst layer 107 does not dilute.
[0052]
The flow rate of the humidified and cooled purified exhaust gas 103 into the purification tower is 0.5 to 5 m / s, preferably 1 to 3 m / s. This is because if the flow velocity is higher than 5 m / s, the pressure loss increases, while if it is lower than 0.5 m / s, the installation area increases, which is not preferable.
[0053]
For example, when SOx in the exhaust gas is 100 ppm, 1 m of activated carbon fiber of the catalyst layer 107 is used.³The processing gas amount is 4000m³About N / h can be processed. In this case, the height of the catalyst layer 107 is about 0.5 m,³What is necessary is just to constitute the catalyst layer 107 of a degree.
[0054]
In addition, efficient operation of water can be achieved by using the supernatant water obtained in the sedimentation tank 20 when the gypsum slurry 19 is generated as the humidification cooling water supplied to the humidification cooling device 116. it can.
As a result, after the sediment remaining in the supernatant water from which the gypsum 22 is separated from the gypsum slurry 19 is settled, the filtered filtrate is used in the humidification cooling device 116 as the humidification cooling water 115 by the liquid sending pump. Gypsum or the like is prevented from adhering to the activated carbon fibers constituting the catalyst layer 107, and as a result, desulfurization efficiency does not decrease and desulfurization performance can be stably maintained over a long period of time. .
[0055]
Further, by separately performing the treatment of the low-concentration SOx as in the present invention, the degree of freedom in selecting the conditions is improved. In addition, in the addition of water in an existing desulfurization device, the generated diluted sulfuric acid 106 can be used as added water for cooling. This is because the sulfuric acid concentration is low and can be used in the same manner as ordinary cooling water.
[0056]
By using the exhaust gas treatment apparatus according to the present embodiment, the cost can be reduced by 15 to 50% as compared with the case of a conventional desulfurization apparatus including only a desulfurization apparatus.
[0057]
[Second embodiment]
Next, an exhaust gas treatment apparatus according to a second embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 5, the exhaust gas treatment apparatus according to the present embodiment is obtained by introducing exhaust gas 101 from a boiler 100 or the like, uses an absorbent (eg, gypsum slurry) 12 containing a calcium compound, and contains a sulfur component. An absorption tower 13 that makes the exhaust gas 101 come into contact with the filler 13a, a liquid storage chamber 15 that stores the slurry 14 that has come into contact with the exhaust gas 101, and an oxygen-containing gas (O₂And an activated carbon fiber layer provided on the downstream side of the filler 13a of the absorption tower 13 for further purifying the purified exhaust gas 103 whose sulfur oxide has been softened by the absorbent. , A water supply means 111 for supplying water 105 for producing sulfuric acid to the catalyst layer 107, and a slurry 14 withdrawn from the liquid storage chamber 15 to remove the filler 13 a of the absorption tower 13. A circulating pump 18 for supplying the slurry 14 from the upper part by a watering nozzle 25, a sedimentation tank (thickener) 20 for sedimenting the gypsum slurry 19 supplied from the liquid reservoir 15 via the pump 16, And a dehydrator 23 which removes the wastewater (filtrate) 21 to obtain a gypsum 22.
[0058]
Next, an exhaust gas treatment device in which a flue gas desulfurization device and a purification device are integrated will be described with reference to FIG. As shown in FIG. 5, after sulfur oxides in the exhaust gas are desulfurized by the absorption tower 13 to obtain diluted sulfuric acid, a lime slurry is supplied to the diluted sulfuric acid to obtain a gypsum slurry, and then dewatered to form gypsum. To use.
At this time, by contacting the filler 13 a of the absorption tower 13 with the absorbent 12, the sulfur oxides which are purified and slightly remain in the purified exhaust gas 103 are purified by the catalyst layer 107 which is a purification means, and the sulfur oxides are purified. The purified gas 109 is hardly used. The diluted sulfuric acid produced in the catalyst layer 107 is used for adjusting the pH under the oxidizing conditions in the liquid storage chamber 15 provided below the absorption tower 13.
In this integrated exhaust gas purification device, the above-described reaction I and reaction II occur simultaneously in the tower. At this time, since the sulfur oxides in the purified gas 103 are oxidized by the catalyst layer 107 into dilute sulfuric acid, the pH is maintained at 5 or less by the dilute sulfuric acid, and the progress of the “reaction II” described above proceeds. It will proceed.
[0059]
[Third Embodiment]
Next, an exhaust gas treatment system including an exhaust gas treatment device according to a third embodiment will be described with reference to FIG.
As shown in FIG. 6, an exhaust gas treatment system according to the present embodiment includes a boiler 100 that generates steam for driving a steam turbine, and a denitration unit 201 that removes nitrogen oxides in exhaust gas 101 from the boiler 100. A dust collector 202 for removing dust in the exhaust gas 101 after denitration, a pushing fan 203 for supplying the exhaust gas 101 thus removed to the inside of the tower 13, and an exhaust gas before (or in the tower) for supplying the exhaust gas 101 to the adsorption tower 4. A humidifying cooling device 116 that cools and increases the humidity of the gas turbine 101 and an absorbent (eg, gypsum slurry) 12 containing a calcium compound supplied from a lime tank 204 by a liquid feed pump 205 are used. An absorption tower 13 to be brought into contact with the filler 13a; A liquid storage chamber 15 for storing, an oxidizing means for supplying an oxygen-containing gas to the slurry 14 in the liquid storage chamber 15, and a sulfur oxidizing means provided on the downstream side of the filler 13 a of the absorption tower 13. A catalyst layer 107 formed of an activated carbon fiber layer for further purifying the purified exhaust gas 103 softened, a water supply means 111 for supplying water 105 for sulfuric acid generation to the catalyst layer 107, and a liquid storage chamber 15. A circulating pump 18 for extracting the slurry 14 from the upper part of the filler 13a of the absorption tower 13 and supplying the slurry 14 by a watering nozzle 25, and a gypsum slurry 19 from the liquid storage chamber 15 are supplied by a pump 16, A sedimentation tank (thickener) 20 for sedimenting the gypsum slurry 19, a dehydrator 23 for removing gypsum 22 by removing water from the gypsum slurry 19 as drainage (filtrate) 21, It is intended to include a.
Note that a mist eliminator 206 may be interposed, if necessary, in a line for discharging the purified purified gas 109 to be separated from the exhaust gas.
[0060]
Here, in the boiler 100, for example, a fuel f such as coal or heavy oil is burned in a furnace in order to generate steam for driving a steam turbine (not shown) of the thermal power generation facility. The exhaust gas of the boiler 100 contains sulfur oxides (SOx), and the exhaust gas is denitrated in advance by a denitration means 201, cooled by a gas gas heater, and then removed by a dust collector 202 such as a bag filter or an electric dust collector. I have. Note that the denitration means 201 may be installed as needed.
[0061]
According to the above system, the desulfurization efficiency of the exhaust gas 101 discharged from the boiler 100 is improved by the purifying means having the catalyst layer 107 integrated into the desulfurization device using the adsorption tower 13 as in the related art. Since the pH can be maintained at 5 or less by the action of sulfuric acid 106, the quality of gypsum production by the lime-gypsum method is improved.
[0062]
【The invention's effect】
As described above, according to the present invention, a flue gas desulfurization device that removes sulfur oxides in exhaust gas, and a purified gas that is provided downstream of the flue gas desulfurization device and that is discharged from the flue gas desulfurization device A purification tower that circulates, a catalyst layer provided in the purification tower, and formed of an activated carbon fiber layer, and a water supply unit that supplies water for sulfuric acid generation to the catalyst layer,
Since sulfuric acid supply means for supplying the generated diluted sulfuric acid to the flue gas desulfurization device is provided, the reaction efficiency can be improved by supplying the diluted sulfuric acid to the flue gas desulfurization device using the obtained diluted sulfuric acid. .
[Brief description of the drawings]
FIG. 1 is a schematic diagram of an exhaust gas treatment apparatus according to a first embodiment.
FIG. 2 is a schematic diagram of an exhaust gas treatment apparatus provided with a purification tower in the lime-gypsum treatment facility according to the present embodiment.
FIG. 3 is a schematic diagram of a purification tower according to the present embodiment.
FIG. 4 is a perspective view of an activated carbon fiber layer according to the present embodiment.
FIG. 5 is a schematic diagram of an exhaust gas treatment apparatus according to a second embodiment.
FIG. 6 is a schematic diagram of an exhaust gas treatment apparatus according to a third embodiment.
FIG. 7 is a schematic diagram of a flue gas desulfurization apparatus of a lime-gypsum treatment method.
[Explanation of symbols]
100 boiler
101 Exhaust gas
102 Flue gas desulfurization equipment
103 Purified exhaust gas
104 Purification Tower
105 water
106 Dilute sulfuric acid
107 catalyst layer
108 sulfuric acid supply means
109 Purified gas
110 chimney

Claims (8)

Flue gas desulfurization equipment for removing sulfur oxides in exhaust gas,
A purification tower that is provided on the downstream side of the flue gas desulfurization device and circulates a purification gas discharged from the flue gas desulfurization device;
A catalyst layer provided in the purification tower and formed of an activated carbon fiber layer,
Water supply means for supplying water for sulfuric acid generation to the catalyst layer,
An exhaust gas treatment apparatus comprising: sulfuric acid supply means for supplying the generated diluted sulfuric acid to the flue gas desulfurization apparatus. Using a slurry containing a calcium compound, an absorption tower that is brought into contact with exhaust gas containing a sulfur component,
A liquid storage chamber for storing the slurry after contact with the exhaust gas,
Oxidizing means for supplying an oxygen-containing gas to the slurry,
A circulation pump for extracting the slurry from the liquid storage chamber and supplying the slurry to the absorption tower;
A purification tower that circulates the purification gas discharged from the absorption tower,
A catalyst layer provided in the purification tower and formed of an activated carbon fiber layer,
Water supply means for supplying water for sulfuric acid generation to the catalyst layer,
An exhaust gas treatment apparatus comprising: sulfuric acid supply means for supplying the generated diluted sulfuric acid to the oxidation means. In claim 1,
An exhaust gas treatment device comprising the absorption tower and the purification tower integrated. An absorption tower that uses a slurry containing a calcium compound to contact an exhaust gas containing a sulfur component through a filling tank,
A liquid storage chamber for storing the slurry after contact with the exhaust gas,
Oxidizing means for supplying an oxygen-containing gas to the slurry,
A circulation pump for extracting the slurry from the liquid storage chamber and supplying the slurry to the absorption tower;
A catalyst layer formed of an activated carbon fiber layer that is provided on the downstream side of the packed tank in the absorption tower and flows the purified gas,
An exhaust gas treatment apparatus comprising: a water supply unit that supplies water for producing sulfuric acid to the catalyst layer. In any one of claims 1 to 4,
An exhaust gas treatment apparatus characterized in that the mist particle diameter in the exhaust gas subjected to the humidification cooling is 50 to 150 μm. In any one of claims 1 to 5,
A humidification cooling device having an inlet for exhaust gas containing sulfur oxide at a lower portion of the purification tower, an outlet for the exhaust gas at an upper portion, and humidifying and cooling the exhaust gas supplied into the purification tower. An exhaust gas treatment device comprising: In claim 6,
An exhaust gas treatment device, wherein the humidification cooling device is provided on the upstream side of a purification tower. In claim 6,
An exhaust gas treatment apparatus characterized in that the humidification cooling device is provided on the upstream side of a catalyst layer in a purification tower.

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