JPH11347362A - Catalytic board for flue gas desulfurization - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the holding amount of moisture in a core board and thereby promote a desulfurization reaction to obtain sulfuric acid through a chemical reaction between water and SO2 by opening plural holes through both faces of the core board and at the same time, filling each of the holes with an active carbon fiber to form a coated layer on both faces of the core board. SOLUTION: A core board 1 is formed of a material such as a glass fiber with an appropriately set thickness and also plural holes 2 with an appropriately shaped cross section and an appropriate set diameter, opened by punching or the like through both faces of the core board 1. Further, each of the holes 2 is filled internally with an active carbon fiber 3 and at the same time, an active carbon fiber layer 4, 5 is formed on each of the both faces of the core board 1. Thus both active carbon fiber layers 4, 5 are allowed to communicate with each other by the active carbon fiber 3, so that the smooth penetration of moisture into the interior of the core board 1 is achieved to increase the holding amount of the moisture. Consequently, it is possible to oxidize SO2 into SO3 with the help of the active carbon fiber as a catalyst and at the same time, promote a desulfurization reaction to obtain sulfuric acid through a chemical reaction between the SO3 and water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the boiler for burning various fuels, for flue gas desulfurization to be used for removing a gas turbine, engine, sulfur oxides in exhaust gas discharged from a combustion furnace or the like (SO _X) It relates to a catalyst board.

[0002]

2. Description of the Related Art Hitherto, as a method for removing sulfur oxides from exhaust gas, a lime-gypsum method of recovering sulfur content as gypsum using limestone or slaked lime slurry as an absorbent has been adopted. As another method, an adsorption method using activated carbon is known.

[0003]

The conventional lime-gypsum process requires large amounts of water and sulfur oxide absorbents.
For this reason, the size and complexity of the desulfurization equipment cannot be avoided.
In addition, in the case of the adsorption method using activated carbon, a large amount of water is required because sulfur adsorbed on activated carbon is desorbed by washing with water. In addition, in the case of this method, it is necessary to discard the generated dilute sulfuric acid and to dry the adsorbent. We have:
Results of studying a simple flue gas desulfurization process that does not require an absorbent and large desulfurization of sulfur oxides, the desulfurization reaction activated carbon fiber as a catalyst to oxidize the SO ₂ in the flue gas to SO _3, further SO They have found a way to obtain sulfuric acid by reacting ₃ with water. The present invention provides a flue gas desulfurization catalyst board for performing this method more efficiently.

[0004]

According to the present invention, there is provided a flue gas desulfurization catalyst board comprising a core board having a large number of holes penetrating on both sides, filling the inside of the hole of the core board, and The core board is made of activated carbon fibers for a desulfurization reaction forming a coating layer on both sides (claim 1).

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A core board used in the present invention is made of a material such as glass fiber or polypropylene fiber. The thickness of the core board is usually 0.1 to 1.0 m
m. The core board has a number of holes penetrating on both sides thereof. The hole is for connecting the activated carbon fiber for desulfurization reaction filled therein and the activated carbon fiber layer for desulfurization reaction formed on both surfaces of the core material board, and can take any cross-sectional shape. . Examples of a core board having a large number of holes penetrating both sides include a punched glass fiber board, a mesh board made of glass fiber, and the like.

When a punched board is used as the core board, the diameter of the holes is, for example, about 0.2 to 5 mm, and the distance between the holes is the distance between the centers.
It is about 0.5 to 10 mm. When a mesh board is used as the core board, the diameter of the core wire is, for example, about 0.05 to 0.2 mm, and the spacing between the meshes (grid spacing) is, for example, about 0.1 to 2 mm. It is. FIG. 1 is a cross-sectional view of a desulfurization catalyst board when a punched board is used as a core board. In FIG. 1, the inside of a large number of holes 2 of a core board 1 is filled with activated carbon fibers 3 for desulfurization,
Activated carbon fiber layers 4 and 5 for desulfurization reaction are formed on both surfaces of.

[0007] The flue gas desulfurization catalyst board of the present invention (hereinafter simply referred to as "catalyst board") has a structure in which activated carbon fiber layers for desulfurization reaction formed on both sides of the core board have holes in the core board. Since the structure is connected by the activated carbon fiber for the desulfurization reaction, the moisture permeates well into the catalyst board. That is, as compared with the case where the activated carbon fiber layers for desulfurization reaction are formed on both sides of the core board having no holes, the amount of retained water at an arbitrary depth from the surface of the catalyst board is increased, and the desulfurization reaction is accelerated. Is done. In addition, the adhesion of the activated carbon fiber layer for the desulfurization reaction to the core board increases.

The activated carbon fiber for desulfurization reaction used in the present invention functions as a catalyst when SO ₂ in exhaust gas is oxidized to SO ₃ . The method for producing the activated carbon fiber for desulfurization reaction used in the present invention will be described below. The type of activated carbon fiber used as a raw material is not particularly limited, and active carbon fibers such as pitch-based, polyacrylonitrile-based, phenol-based, and cellulose-based activated carbon fibers can be used. Among these, those having higher hydrophobicity on the surface of the activated carbon fiber are particularly desirable, and specific examples thereof include pitch-based activated carbon fiber.

Activated carbon fibers are usually heat-treated at a temperature of about 600 to 1200 ° C. in a non-oxidizing atmosphere such as nitrogen gas. The processing time may be appropriately determined according to the processing temperature and the like. By this heat treatment, the carbon fiber for desulfurization reaction used in the present invention can be obtained. The activated carbon fiber for the desulfurization reaction has a surface that is more hydrophobic than that before the treatment, since part or all of the hydrophilic oxygen functional groups are removed as CO, CO _2, or the like by heat treatment. Therefore, it occurs readily snapping SO ₂ to oxidized active sites SO _2, yet produced results that discharge also proceeds rapidly sulfate, without the function of the catalyst is inhibited, the desulfurization reaction is accelerated.

A specific example of a production example of an activated carbon fiber for a desulfurization reaction is as follows, for example. Specific Example 1 A pitch-based activated carbon fiber (“OG-20A”, manufactured by Adol Co., Ltd.) was used in a nitrogen atmosphere at 900 to 1,
Baking is performed for 1 hour in a temperature range of 200 ° C. Specific Example 2 Polyacrylonitrile-based activated carbon fiber (“FE-30
0 "(manufactured by Toho Rayon Co., Ltd.) and fired in a nitrogen atmosphere within a temperature range of 800 to 1200 ° C. for 1 hour.

The activated carbon fibers for desulfurization reaction used in the present invention generally have a thickness of 7 to 20 μm and a specific surface area of 5 μm.
00 to 2,500 m ² / g, outer surface area 0.2 to 2.0
m ² / g, and the pore diameter is 45 Å or less. Table 1 shows the composition formulas and the like of the activated carbon fibers for each of the pitch-based, polyacrylonitrile-based, phenol-based, and cellulose-based desulfurization reactions. Note that the numerical values in Table 1 indicate only normal values, and there may be values outside these numerical ranges.

[0012]

[Table 1]

The method for producing the flue gas desulfurization catalyst board of the present invention is as follows. A mesh board or a punching board is used as a core material, and activated carbon fiber layers (boards) are combined on both sides, and heated (80 to 110 ° C) and pressurized (3 to
Fusing under 10 kg / cm ² G).

An example of a flue gas desulfurization system using the flue gas desulfurization catalyst board of the present invention will be described with reference to FIG.
In FIG. 1, an exhaust gas containing sulfur oxides discharged from a boiler 11 is cooled by a gas-gas heater (GGH) 13, then is dust-removed in a dust collector (ESP) 14, and passes through a fan 12. From the inlet 15 to the absorption tower 16
Introduced within. The temperature of the exhaust gas at the time of introduction into the absorption tower 16 is about 90 ° C. The exhaust gas introduced into the absorption tower comes in contact with water sprayed from a water sprayer 17 for humidifying and cooling the exhaust gas, and is cooled to 70 ° C. or lower, and the relative humidity increases. Condition (relative humidity = 100%)
Becomes Here, if the temperature exceeds 70 ° C., the amount of evaporation of water in the activated carbon fiber layer for desulfurization increases, and there is a disadvantage that the supply amount of water must be increased.

The exhaust gas which has been subjected to the humidified cooling is supplied to the activated carbon fiber layer 18 for desulfurization reaction filled in the central portion of the absorption tower 16.
Passing down inside. In addition, the activated carbon fiber layer 18 for desulfurization reaction is
Is supplied by a water supply device 19 provided above or in the vicinity of the activated carbon fiber so that water adheres to the surface of the activated carbon fiber. Here, the activated carbon fiber layer for desulfurization reaction 18
For example, the catalyst board of the present invention can be formed by arranging a large number of the catalyst boards of the present invention in a box-shaped frame at regular intervals in an absorption tower.

SO ₂ in the exhaust gas is converted into oxygen (O ₂ ) in the exhaust gas on the surface of the activated carbon fiber for the desulfurization reaction acting as a catalyst.
₂ ) and is oxidized to SO ₃ . Generated SO
₃ reacts with water adhering to the activated carbon fiber for desulfurization reaction to form sulfuric acid (H ₂ SO ₄ ). The generated sulfuric acid falls from the activated carbon fiber layer for desulfurization reaction 18 and is absorbed by the absorption tower 16.
Is discharged from the bottom of the tank and passed through the pump 20 to be in the sulfuric acid storage tank 2.
Stored in 1 and used for industry.

As the water for humidifying and cooling the exhaust gas, water introduced from outside the system is used, or water (dilute sulfuric acid) discharged from the lower part of the absorption tower is circulated by a pump 22 as shown in the figure. Can be used. The use of circulating water can reduce the amount of water used. Similarly, as the water supplied to the activated carbon fiber layer 18 for desulfurization reaction for producing sulfuric acid, water from outside the system or circulating water discharged from the absorption tower can be used. The water sprayer 17 for humidifying and cooling the exhaust gas and the water supplier 19 for generating sulfuric acid to the activated carbon fiber layer for the desulfurization reaction may be shared. Absorption tower 16
Exhaust gas desulfurized in the exhaust port 2
3, and after being heated by the gas-gas heater 13, is discharged from the chimney 24.

[0018]

According to the flue gas desulfurization catalyst board of the present invention, the amount of water retained in the board is increased, and the desulfurization reaction is accelerated.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a flue gas desulfurization catalyst board of the present invention.

FIG. 2 is a schematic view showing an example of a flue gas desulfurization system using the desulfurization catalyst board of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 core board 2 hole 3 activated carbon fiber for desulfurization reaction 4,5 activated carbon fiber layer for desulfurization reaction 11 boiler 12 fan 13 gas-gas heater 14 dust collector 15 inlet 16 absorption tower 17 water sprayer 18 for desulfurization reaction Activated carbon fiber layer 19 Water supplier 20 Pump 21 Sulfuric acid storage tank 22 Pump 23 Outlet 24 Chimney

Claims (1)

[Claims] A core board having a large number of holes penetrating both sides thereof, and a desulfurization reaction for filling the inside of the holes of the core board and forming coating layers on both sides of the core board A flue gas desulfurization catalyst board comprising activated carbon fibers.