JPH0966222A - Treatment of exhaust gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a problem of the leak of ammonia in the treatment of exhaust gas even if exhaust gas low in SOx concn. is treated with a carbonaceous catalyst. SOLUTION: The carbonaceous catalyst subjected to desulfurization and denitration treatment in a reactor 2 to be deactivated is introduced into a regenerator 6 to be regenerated under heating and activated by ammonia gas- containing inert gas. SOx is added to the activated carbonaceous catalyst and the SOx added carbonaceous catalyst is utilized in the treatment of exhaust gas. In order to further enhance catalytic activity as compared with this exhaust gas treatment method, it is desirable to preliminarily apply SOx adding treatment to the deactivated carbonaceous catalyst before heated and regenerated by the regenerator 6 in addition to the above-mentioned method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating exhaust gas, which comprises desulfurizing and denitrifying exhaust gas containing sulfur oxides and nitrogen oxides with a carbonaceous catalyst, and then regenerating the inactivated carbonaceous catalyst.

[0002]

2. Description of the Related Art Conventionally, ammonia is injected into combustion exhaust gas discharged from a boiler containing SO _X , NO _X , a sintering furnace in a steel mill, a refuse incinerator, etc., and activated carbon, activated coke, or activated carbon A method of treating exhaust gas by passing it through a cross-flow type moving bed reactor packed with a high-quality catalyst is well known. The dry exhaust gas treatment method using such a carbonaceous catalyst does not have problems such as securing water for use, waste water treatment, and lowering of exhaust gas temperature as in the wet method, and at the relatively low temperature, only sulfur oxide (SO _X ). Nitrogen oxides (NO _x ) can be removed, and the carbonaceous catalyst can be easily regenerated by simple heating regeneration, as well as harmful chlorine compounds such as dioxins and volatile heavy metals such as mercury which have become a problem recently. It has the advantage of being removable.

In this method of injecting ammonia into the exhaust gas and treating with a carbonaceous catalyst, the removal of SO _{x in} the exhaust gas utilizes the adsorption action of the carbonaceous catalyst, so the treatment temperature is preferably lower, but NO _{Since X} is removed by reaction with ammonia, the higher the treatment temperature is, the more preferable as in the high temperature denitration using a titanium-based catalyst. On the other hand, when the treatment temperature is high (about 200 ° C. or higher), the carbonaceous catalyst itself reacts with oxygen in the exhaust gas and is consumed, so high temperature treatment must be avoided. Therefore, the temperature of boiler exhaust gas is generally 130 to 1
Since the temperature is around 50 ° C, it is often operated in the temperature range around this.

Since the carbonaceous catalyst used in the desulfurization / denitration method of exhaust gas is inactivated and its adsorption capacity is lowered, it is heated and regenerated by a regenerator and used again for desulfurization / denitration. However, the adsorption capacity of the carbonaceous catalyst gradually decreases even after the regeneration treatment. The present inventor has already clarified that it is effective to bring the regenerated adsorbent into contact with ammonia gas to activate it in order to prevent such a decrease in adsorption capacity (Japanese Patent No. 1313218). , JP-A-60-220129).

[0005]

However, in the above-mentioned conventional desulfurization / denitration method using a carbonaceous catalyst, the treatment is carried out at a relatively low temperature (that is, around 130 to 150 ° C.) which is not very advantageous for the denitration treatment. In many cases, the amount of ammonia injected into the exhaust gas is increased in order to improve the denitration performance, which causes a problem that unreacted ammonia leaks into the process gas.

Further, in the conventional desulfurization / denitration method in which the exhaust gas into which ammonia is injected is passed through a cross-flow type moving bed reactor filled with a carbonaceous catalyst, in the treated gas passing through the upper part of the reactor, There is a problem that a large amount of Annimore is mixed. In order to solve this problem, the present inventor reduced the amount of annimore injected into the exhaust gas passing through the upper part of the reactor to be smaller than the amount of annemore injected into the exhaust gas passing through the lower part, so that A method for reducing the amount has already been proposed (Japanese Patent Laid-Open No. 59-209630).
However, this method has a problem that the structure of the reactor becomes complicated.

Further, the conventional method for activating the regenerated carbonaceous catalyst by contacting it with ammonia is such that even if the activated carbonaceous catalyst is returned to the reactor and reused, the treatment passed through the upper portion of the reactor is performed. There is a problem that a large amount of ammonia is mixed in the gas.

The exhaust gas is passed through the conventional cross-flow type moving bed reactor, and in the process gas treated, ammonia is added to the process gas passing through the upper part of the cross-flow type moving bed reactor. Many causes are considered as the following (i) to (iii). (I) In the upper part of the reactor, the contact time between the supplied carbonaceous catalyst and the exhaust gas is short, so that the amount of sulfuric acid adsorbed on the carbonaceous catalyst in the upper part of the reactor is small, and therefore, ammonia is injected into the exhaust gas. However, it is conceivable that ammonia cannot be completely collected by sulfuric acid and becomes ammonia gas in the processing gas and flows out.

(Ii) When the carbonaceous catalyst is heated and regenerated in the regenerator, a reducing substance is produced on the carbonaceous catalyst. When carbonaceous catalyst having such reducing substance is supplied to the reactor top, the carbonaceous catalyst in the top of the reactor to react with NO _X. Therefore, it is conceivable that the annimore injected into the exhaust gas becomes excessive and leaks.

The phenomenon of leakage in the upper part of the reactor is very complicated and is not clear at present, but it can be inferred as follows. That is, a part of the injected annimore reacts with H ₂ SO ₄ on the catalyst to carry out the reactions of the following formulas (1) and (2), and is captured as a sulfate on the carbonaceous catalyst. .

[0011]

Embedded image

The rest of the Annimore is present in the exhaust gas, N
By reacting with O, the reaction of the following formula (3) is performed, ammonia is consumed and contributes to denitration.

[0013]

Embedded image

On the other hand, since the carbonaceous catalyst circulating from the regenerator contains a reducing substance (Ac), this reducing substance (Ac) is also denitrified in the same manner as ammonia by the following formula (4). Have contributed.

[0015]

Embedded image (R: a reducing substance such as H, NH, NH ₂ , Ac ... R means a reducing substance on the carbonaceous catalyst, and the formula (4) represents a tentative reaction formula.) Reduction in the upper part of the reactor Since a large amount of the volatile substance is present and this reducing substance reacts with NO, the formula (4) has priority over the formula (3), and therefore the consumption of ammonia by the formula (3) is small. Therefore, it is considered that the amount of ammonia leakage increases in the upper part of the reactor.

(Iii) In the method of further activating the regenerated carbonaceous catalyst with ammonia, a larger amount of reducing substances are produced on the surface of the carbonaceous catalyst as compared with the case of simply regenerating by heating,
The phenomenon described in (ii) above occurs more significantly. That is,
Since the reducing substance plays the role of ammonia and contributes to the denitration reaction, ammonia becomes excessive. In addition to this phenomenon, when the carbonaceous catalyst is activated by ammonia, part of the ammonia is adsorbed by the carbonaceous catalyst, and when such a carbonaceous catalyst is supplied to the reactor, the ammonia is removed by purging the exhaust gas. It is thought to leak.

The present inventors have in particular the following (a),
In the cases of (b) and (c), it was found that the leakage of ammonia was remarkable in the process gas treated with the carbonaceous catalyst existing in the upper part of the reactor.

(A) When an exhaust gas having a low SO _X concentration is introduced into the reactor (b) A step of regenerating a carbonaceous catalyst which has been deactivated by using it for treating the exhaust gas in order to improve the catalytic activity of the carbonaceous catalyst Before, SO _X and ammonia were adsorbed on the carbonaceous catalyst so as to increase its adsorption amount, and then the carbonaceous catalyst was regenerated to obtain a carbonaceous catalyst that produced a large amount of reducing substances on the surface, When this is introduced into the reactor (c) In order to improve the catalytic activity of the carbonaceous catalyst, the carbonaceous catalyst is activated by contacting with ammonia,
When a carbonaceous catalyst that produces a large amount of reducing substances on the surface is used and introduced into a reactor, especially when treating an exhaust gas having a low SO _X concentration as described in (a) above with a carbonaceous catalyst, carbon is added. There is a problem that ammonia leakage becomes extremely conspicuous when the above cases (b) and (c) for activating the quality catalyst are overlapped.

Therefore, in the present invention, the exhaust gas is treated with a carbonaceous catalyst to regenerate the deactivated carbonaceous catalyst, and further NH ₃
In the exhaust gas treatment method in which the carbonaceous catalyst is activated by, and the activated carbonaceous catalyst is used again as a catalyst, an object thereof is to provide an exhaust gas treatment method capable of improving the problem of ammonia leakage in the reactor. To do. In particular, an object of the present invention is to provide a method for treating exhaust gas that can solve the problem of ammonia leakage when treating exhaust gas having a low SO _X concentration with a carbonaceous catalyst.

[0020]

In order to solve the above problems, the method for treating exhaust gas according to the present invention is such that ammonia is injected or not injected into exhaust gas containing sulfur oxides and nitrogen oxides. Then, desulfurization and denitration treatment is performed in a cross-flow type moving bed reactor filled with a carbonaceous catalyst, and the carbonaceous catalyst inactivated in the reactor is regenerated by a moving bed type regenerator, and the carbonaceous catalyst is treated with ammonia. Is activated, the activated carbonaceous catalyst is again used as a carbonaceous catalyst for exhaust gas treatment, and in the exhaust gas treatment method used by filling the reactor, SO _X is added to the activated carbonaceous catalyst, The carbonaceous catalyst to which the SO _X is added is used for exhaust gas treatment.

According to the present invention, since the carbonaceous catalyst is activated by ammonia, it has the effect of increasing the catalytic activity, and at the same time SO _X is adsorbed and adsorbed on the surface of the carbonaceous catalyst. Return the carbonaceous catalyst to the reactor,
Even if the desulfurization and denitration treatment of the exhaust gas is performed again, the ammonia is sufficiently captured by the carbonaceous catalyst, so that there is no risk of ammonia leaking into the treatment gas in the upper part of the reactor.

In the method for treating exhaust gas of the present invention, in order to further enhance the catalytic activity as compared with the above method, in addition to the above method, the deactivated carbonaceous catalyst before being heated and regenerated by the regenerator is preliminarily SO 2. It is desirable to add _X.

The carbonaceous catalyst referred to in the present invention includes activated carbon and
Commonly mentioned are carbonaceous catalysts such as activated coke particles obtained by activating coal with heat treatment or steam, etc., but those having metal oxides such as vanadium, iron and copper supported on these carbonaceous catalysts are also available. Applicable.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described with reference to FIGS. 1 to 3 showing the treatment process of exhaust gas containing SO _X and NO _X.

In the treatment process of FIG. 1, 60 to 180 ° C.
The temperature-controlled exhaust gas is directly introduced into the cross-flow moving bed reactor 2 through the exhaust gas introduction line 1. Alternatively, ammonia is introduced into the exhaust gas introduction line 1 via the ammonia introduction line 3 and the exhaust gas into which the ammonia has been introduced is introduced into the reactor 2. The exhaust gas is desulfurized and denitrified by contacting the carbonaceous catalyst 4 descending from the top to the bottom in the reactor 2 and then desulfurized and denitrated. Is released.
The carbonaceous catalyst inactivated in the reactor 2 (abbreviated as inactivated carbonaceous catalyst) is extracted from the bottom of the reactor 2 and passed through the top valve V ₁ provided at the top of the regenerator 6 to regenerator 6
Supplied within.

The deactivated carbonaceous catalyst supplied to the regenerator 6 is passed through the storage area 7 and the separation area 8 and a plurality of heat transfer tubes 10 arranged substantially vertically in the heat exchange area 9 as a moving bed. Run down. On the other hand, on the heating side in the heat exchange area 9, that is, on the outside of the heat transfer tube 10, the heating gas supplied from the heating gas introduction line 11 is passed upward and is inactivated while flowing down in the heat transfer tube 10. Carbonaceous catalyst is about 350
It is heated to a regeneration temperature of ~ 600 ° C. The inactivated carbonaceous catalyst heated to the regeneration temperature is regenerated by releasing sulfur dioxide, sulfur trioxide, ammonia, etc., and moves to the ammonia gas-containing inert gas introduction region 12.

Inert gas introduction region 1 containing ammonia gas
2 to the ammonia introduction line 13 from NH ₃ , N ₂ , C
An ammonia gas-containing inert gas diluted with a combustion exhaust gas having a low concentration of O ₂ , steam or oxygen is supplied. The ammonia gas-containing inert gas rises in the heat transfer tube 10 with the gas desorbed from the inactivated carbonaceous catalyst and reaches the separation region 8 where the inactivated carbonaceous catalyst at a relatively low temperature stays.

Generally, the inactivated carbonaceous catalyst that is subjected to the heating regeneration usually has a surplus capacity for adsorption.
Ammonia in the above-mentioned desorbed substance and ammonia in the above-mentioned desorbed substance which have reached the separation region 8 due to the inert gas are treated as sulfates, and sulfur trioxide in the above-mentioned desorbed substance is treated as sulfuric acid. Captured by the catalyst. Therefore, a high-concentration sulfur dioxide gas containing no ammonia or sulfur trioxide can be taken out from the separation region 8 through the desorbed gas discharge line 14.

When the gas that has risen to the separation region 8 along with the desorbed substances enters the storage region 7, corrosion of the regenerator 6 due to dew condensation or the like may occur. By additionally supplying an inert gas from the inert gas introduction line 16 to the vicinity of the rectifying body 15 provided in the area 7, it is possible to prevent the gas accompanying the desorbed material from entering the storage area 7. You can Even if this intrusion occurs, dew condensation can be prevented by installing a heater (not shown) near the rectifying body 15.

The carbonaceous catalyst (referred to as a regenerated carbonaceous catalyst) that is heated and regenerated in the heat transfer tube 10 and released from the desorbed substances in the ammonia gas-containing inert gas introduction region 12 is a cooler 17.
After flowing down the inside and being cooled by indirect heat exchange with a suitable cooling medium (air or water etc.), it is taken out from a bottom valve V ₂ provided at the bottom of the regenerator 6. If necessary, in order to purge the ammonia gas adsorbed on the regenerated carbonaceous catalyst and to purge the gas that has entered the cooling region 18 from the ammonia gas-containing inert gas introduction region 12, the ammonia gas-containing inert gas may be used. From the inert gas introduction line 19 arranged in the introduction area 12, and the cooling area 1
Inert gas is introduced into each region from the inert gas introduction line 20 arranged in FIG.

The regenerated carbonaceous catalyst discharged from the bottom valve V ₂ is treated with a screen (not shown) for separating dust and the like, and then SO _X (sulfuric acid) is adsorbed and added.
As a method for adsorbing and adding SO _X , concentrated sulfuric acid or dilute sulfuric acid aqueous solution is sprayed on the regenerated carbonaceous catalyst, or as shown in FIG.
As shown in, SO ₂ from the SO _X introduction line 21,
A gas containing O ₂ and H ₂ O is introduced into the SO _X adder 22, where SO _X is added to the regenerated carbonaceous catalyst. S
The regenerated carbonaceous catalyst to which O _X has been added is returned to the top of the reactor 2 and used again for exhaust gas treatment. The gas supplied to the SO _X adder 22 is the SO ₂ -containing exhaust gas or the desorbed gas (high-concentration SO 2) which is discharged from the separation region 8 to the desorbed gas discharge line 14 as shown by the dotted line in FIG. _It is possible to use a gas in which an oxygen-containing gas (air or a low oxygen-containing gas) is mixed in all or part of (including ₂ and water).

As the reaction type of the SO _X addition in the SO _X addition device 22, a normal moving bed type, for example, countercurrent type, cocurrent type or crossflow type moving bed type reactor can be used.
SO to be added to the regenerated carbonaceous catalyst in the SO _X adder 22
_X amount is 0.5 to 30 per g of carbonaceous catalyst in terms of SO _2.
It is about mg, more preferably about 2 to 20 mg. _{If the} amount of SO _X to be added is too small, the amount of ammonia gas leaking into the process gas in the reactor 2 increases, and conversely SO 2
_{If the X} addition amount is too large, the temporary poisoning of the carbonaceous catalyst becomes large and the desulfurization and denitration performance in the reactor 2 deteriorates. Note that S
The present invention can be carried out without any problem even if the O _X adder 22 is provided in the lower region of the regenerator 6 instead of being provided separately from the regenerator 6.

In addition, as a reminder, in the embodiment shown in FIG. 1, the deactivated carbonaceous catalyst is allowed to flow in the heat transfer tube 10 and the heat transfer tube 10
The heating gas is flowing outside, but reverse this and heat transfer tube 1
Even in a mode in which the heating gas is flown in 0 and the inactivated carbonaceous catalyst is flown outside the heat transfer tube 10, the inactivated carbonaceous catalyst can be regenerated and activated.

Next, the mode of FIG. 2 will be described.

The purpose of the treatment process of FIG. 2 is to improve the activity of the carbonaceous catalyst more than that of the treatment process of FIG. 1 and to suppress ammonia leakage into the treatment gas of the reactor 2 of the cross flow type moving bed. It is to be. That is, the processing process of FIG. 2, further improve the activity of the reproduction carbonaceous catalyst by a further adsorb SO _X inactivation carbonaceous catalyst which has been supplied to the regenerator 106 is heated and regenerated with an ammonia coexist And, after adsorbing SO _X (sulfuric acid) on the regenerated carbonaceous catalyst having improved activity, it is supplied to the reactor 2 to suppress ammonia leak into the processing gas of the reactor 2. Is the way.

Regenerator 1 used in the treatment process of FIG.
Reference numeral 06 denotes a regenerator 6 used in the processing process of FIG.
In, between the separation region 8 and the heat exchange area 9, SO _X
The additional area 24 is provided. The SO _X addition region 24 is provided with an oxygen-containing gas introduction line 23 for introducing the oxygen-containing gas into the region. Further, to the oxygen-containing gas introduction line 23, SO ₂ and H ₂ which are discharged from the separation region 8 through the desorbed gas discharge line 14.
It is arranged so that O can be mixed and introduced into the SO _X addition region 24. The other device configuration used in the processing process of FIG. 2 is the same as that of FIG.

The treatment process of FIG. 2 is similar to the embodiment shown in FIG. 1, but in order to add more SO _X to the deactivated carbonaceous catalyst, at the top of the regenerator 106 (about 10 heating temperature).
SO _X additional region 24 provided in the 0 to 350 ° C. region)
The oxygen-containing gas is supplied via the oxygen-containing gas introduction line 23 to the SO ₂ (SO ₂ and H ₂ in the desorbed gas which is desorbed from the inactivated carbonaceous catalyst heated in the heat exchange region 9 and rises. _A large amount of ₂ O) is added as SO _X (sulfuric acid) on the deactivated carbonaceous catalyst in the presence of oxygen. Note that SO _X
When it is necessary to increase the addition amount, the separation area 8
Part of the desorption gas separated from the desorption gas introduction line 25
And is supplied to the SO _X addition region 24 via. The deactivated carbonaceous catalyst to which SO _X is added is heated and regenerated in the process of descending in the heat transfer tube 10, and activated by ammonia rising from the lower part in the heat transfer tube 10. As a result, SO _X
The regenerator 106 of FIG. 2 provided with the additional region 24 can significantly improve the catalytic activity as compared with the regenerator 6 of FIG. 1 in which SO _X is not added. Other processes are shown in FIG.
It is performed in the same way as the processing process of.

The total amount of SO _X added to the regenerated and activated carbonaceous catalyst in the treatment process of FIG. 2 is 0.5 to 30 mg per g of carbonaceous catalyst in terms of SO ₂ as in the treatment process of FIG. Degree, more preferably 2 to 20 m
g. _{If the} amount of SO _X to be added is too small, the amount of ammonia gas leaking into the process gas in the reactor 2 will increase, while if the amount of SO _X added is too large, the temporary poisoning of the carbonaceous catalyst will increase and the reaction will increase. The desulfurization and denitration performance in the vessel 2 is reduced.

The treatment process of FIG. 3 is intended to improve the activity of the carbonaceous catalyst as compared with the treatment process of FIG. 1 and to suppress ammonia leakage into the treatment gas of the reactor 2 of the cross flow type moving bed. 2 is a mode different from the processing process of FIG. 2 described above. That is, the processing process of FIG.
In addition to the method of adding SO _{X in} the treatment process of
Before supplying the inactivated carbonaceous catalyst extracted from the lower part of the above to the regenerator 6, the catalyst pretreatment device 26 provided separately adds SO _X to the inactivated carbonaceous catalyst.

The apparatus configuration used in the treatment process of FIG. 3 is the same as the apparatus configuration used in the treatment process of FIG. 1, in which SO _X is used as an inactivated carbonaceous catalyst between the reactor 2 and the regenerator 6. A catalyst pretreatment device 26 for addition is provided.

As a method for adding SO _X to the inactivated carbonaceous catalyst, spraying of concentrated sulfuric acid, diluted sulfuric acid or an aqueous ammonium salt solution of sulfuric acid (ammonium sulfate, acidic ammonium sulfate, etc.) can be carried out on the inactivated carbonaceous catalyst. . Alternatively, as another method of adding SO _X , as shown in FIG. 3, oxygen is contained in a part of the desorbed gas containing SO ₂ and H ₂ O discharged from the separation region 8. Gas (eg air or exhaust gas)
By supplying the gas mixed with the above to the catalyst pretreatment device 26 through the desorption gas introduction line 27, SO _X can be added to the inactivated carbonaceous catalyst.

As the reaction type of the SO _X addition in the catalyst pretreatment device 26, an ordinary moving bed type, for example, countercurrent type, cocurrent type or crossflow type moving bed type reactor can be used. As suitable operating conditions of the catalyst pretreatment device 26, the reaction temperature is 50 to 200 ° C., the SV (exhaust gas amount per unit catalyst amount) is 30 to 5000 h ⁻¹ , and the SO ₂ concentration is 0.05 to ₂
It is about 5%.

In this way, the inactivated carbonaceous catalyst to which SO _X has been added in the catalyst pretreatment device 26 is supplied into the regenerator 6 via the top valve V ₁ of the regenerator 6. Subsequent operations are performed in the same manner as the processing process of FIG.

In each regenerator used in the treatment process of FIGS. 1 to 3, the ammonia introduction line 13 and the desorbed gas discharge line 14 may be reversed. In this case, ammonia gas may be mixed in the desorbed gas, and in that case, a means for separating the ammonia gas with a scrubber or the like is taken.

According to the method for treating exhaust gas of the present invention, since sulfuric acid (SO _X ) is added to the carbonaceous catalyst in advance, the following formula (5) and formula (5) are added in the upper part of the reactor of the cross flow type moving bed. (6)
Reaction by

[0046]

Embedded image (* Indicates the state of adsorption or adhesion on the catalyst surface) and NH ₃ is captured by the carbonaceous catalyst to which SO _X has been added, so that the problem of leakage can be solved.

In the conventional method for treating exhaust gas using a carbonaceous catalyst which does not add SO _X , NH ₃ leak in the upper part of the reactor is, for example, 500 when the SO _X concentration in the exhaust gas is low.
Although it occurred remarkably at ppm or less, particularly 100 to 200 ppm or less, according to the present invention, since the amount of SO _X added on the carbonaceous catalyst is large, it has an effect of trapping NH ₃ considerably. Therefore, the present invention exerts a remarkable effect when the SO _X concentration of exhaust gas is low.

The SO _X to be added to the carbonaceous catalyst in advance
When the amount is excessive, it means to poison the carbonaceous catalyst, the SO _X amount to be added, the exhaust gas properties will vary by the permissible NH ₃ leakage, etc., usually about per carbonaceous catalyst g with SO ₂ in terms It is about 0.5 to 30 mg, more preferably about 2 to 20 mg.

[0049]

【Example】

[Example 1] 150 ppm of sulfur oxide and 200 ppm
The coal-fired boiler flue gas containing nitrogen oxide of was taken out at a flow rate of 600 Nm ³ / h, mixed with 260 ppm of ammonia gas, and then introduced into a cross-flow type moving bed reactor at 135 ° C. In this case, the charged amount of activated carbon (diameter about 8 mm, length about 9 mm) in the reactor was 1.5 m ³ ,
The residence time of activated carbon is set to 70 hours.

The activated carbon used in the reactor and inactivated was fed to the moving bed type regenerator 6 shown in FIG. 1 at 15 kg / h for regeneration and activation. The activated carbon was heated to 500 ° C. in the heat transfer tube 10, and the supply amount of the ammonia gas-containing inert gas (N ₂ gas containing 3% NH ₃ ) from the ammonia introduction line 13 was 0.5 Nm ³ / h, The total amount of inert gas (N ₂ ) supplied from the inert gas introduction lines 16, 19 and 20 was set to 0.5 Nm ³ / h. The activated carbon discharged from the bottom of the regenerator 6 was supplied to the SO _X addition device 22, and the activated carbon was sprayed with 20% dilute sulfuric acid and dried to add SO _X. The SO _X amount of added activated carbon discharged from the SO _X adder 22 was adjusted to 5 mg / g (active carbon) in SO ₂ conversion. This activated carbon was returned to the top of the reactor 2 of the cross flow type moving bed, and continuous operation was performed. As a result of exhaust gas treatment under the above conditions, the desulfurization rate of the treated gas is 100% and the denitration rate is 70%.
%, The ammonia leak in the treated gas was 2 ppm. As a comparative example, the same operation as in Example 1 was carried out except that SO _X was not added, but the desulfurization rate was 100.
%, The denitration rate was 70%, and the ammonia leak in the processing gas was 25 ppm.

[Example 2] Exhaust gas from a coal-fired boiler containing 150 ppm of sulfur oxides and 200 ppm of nitrogen oxides was taken out at 600 Nm ³ / h, to which 260 ppm was added.
After mixing the ammonia gas of Example 1, the mixture was introduced into a cross-flow type moving bed reactor at 135 ° C. In this case, the charged amount of activated carbon (diameter about 8 mm, length about 9 mm) in the reactor was 1.5.
The m ³ and the residence time of the activated carbon are set to 70 hours.

The deactivated activated carbon used in the reactor is fed to the moving bed type regenerator 106 shown in FIG. 2 at 15 kg / h, and the SO _X addition region 24 in this regenerator 106 is supplied.
A gas having an oxygen concentration of 3.5% obtained by diluting air with an inert gas was injected from the oxygen-containing gas introduction line 23. The temperature of the activated carbon is raised to 500 ° C. in the heat transfer tube 10, and the ammonia-containing inert gas (3%
N ₂ gas containing NH ₃ ) of 0.5 Nm ³ /
h, and the total amount of inert gas (N ₂ ) supplied from the inert gas introduction lines 16, 19 and 20 is 0.5 Nm ³ /
h. Activated carbon discharged from the bottom of the regenerator 106 is S
The SO _{X was} added to the O _X adder 22 by spraying activated carbon with 20% dilute sulfuric acid and drying. SO
The SO _X adsorption amount of the activated carbon discharged from the _X addition device 22 is S
It was adjusted to 5 mg / g (activated carbon) in terms of O ₂ . This activated carbon was returned to the top of the cross flow type moving bed reactor 2 and continuously operated. As a result of performing the exhaust gas treatment under the above conditions, the desulfurization rate of the treatment gas was 100%, the denitration rate was 78%, and the ammonia leak in the treatment gas was 2 ppm.

As a comparative example, the same operation as in Example 2 was carried out except that SO ₂ was not added after regeneration, but the desulfurization rate was 100% and the denitrification rate was 78%. The ammonia leak was 30 ppm.

[Example 3] 80 ppm of sulfur oxide and 4
The coal-fired boiler exhaust gas containing 0 ppm of nitrogen oxides was taken out at a flow rate of 600 Nm ³ / h, and 40 pp was added to this.
m of ammonia gas was mixed and then introduced at 135 ° C. into a cross-flow moving bed reactor. In this case, the charged amount of activated carbon (diameter about 8 mm, length about 9 mm) in the reactor is 1.2 m.
^3. The residence time of activated carbon is set to 100 hours.

The activated carbon used in the reactor and inactivated was fed to the moving bed type regenerator 6 shown in FIG. 1 at 8.4 kg / h for regeneration. The activated carbon is heated to 500 ° C. in the heat transfer tube 10, and the supply amount of the NH ₃ gas-containing inert gas (N ₂ gas containing 3% NH ₃ ) from the ammonia introduction line 13 is set to 0.5 Nm ³ / h. , Also inert gas introduction line 1
The total amount of inert gas (N ₂ ) supplied from 6, 19, and 20 was set to 0.5 Nm ³ / h. The activated carbon discharged from the bottom of the regenerator 6 was supplied to the SO _X addition device 22 to which a gas obtained by mixing air with a part of the desorbed gas was supplied to perform SO _X addition. The SO _X amount of added activated carbon discharged from the SO _X adder 22 was adjusted to 4 mg / g (active carbon) in SO ₂ conversion.
This activated carbon was returned to the top of the reactor 2 of the cross flow type moving bed, and continuous operation was performed. As a result of exhaust gas treatment under the above conditions, the desulfurization rate of the treated gas is 100%, the denitration rate is 75%,
The ammonia leak in the treated gas was 1 ppm.

As a comparative example, the same operation as in Example 3 was carried out except that SO _X was not added, but the desulfurization rate was 100%, the denitrification rate was 75%, and the ammonia leak into the treated gas was Was 20 ppm.

Example 4 80 ppm of sulfur oxide and 4
The coal-fired boiler exhaust gas containing 0 ppm of nitrogen oxide was taken out at 600 Nm ³ / h, 40 ppm of ammonia gas was mixed with this, and then introduced into a cross-flow type moving bed reactor at 135 ° C. In this case, the charged amount of activated carbon (diameter about 8 mm, length about 9 mm) in the reactor was set to 1.2 m ³ , and the residence time of activated carbon was set to 100 hours.

The deactivated activated carbon used in the reactor was led to the catalyst pretreatment unit 26 as shown in FIG. 3 to increase the SO _X adsorption amount. A gas prepared by mixing air with a part of the desorbed gas was supplied to the catalyst pretreatment device 26 to increase the SO _X adsorption amount of activated carbon by 10 mg per g of activated carbon in terms of SO ₂ . 8.4 kg / h of this activated carbon was added to the moving bed type regenerator 6.
The temperature of the activated carbon is raised to 500 ° C. in the heat transfer tube 10, and the ammonia-containing inert gas (N ₂ gas containing 3% NH ₃ ) supply amount from the ammonia introduction line 13 is 0.5 Nm. ³ / h, and inert gas introduction line 1
The total amount of inert gas (N ₂ ) supplied from 6, 19, and 20 was set to 0.5 Nm ³ / h. The activated carbon discharged from the bottom of the regenerator 6 was supplied to the SO _X addition device 22 to which a mixed gas of a part of the desorbed gas and air was supplied to perform SO _X addition.
The SO _X amount of adsorbed activated carbon discharged from the SO _X adder 22 is adjusted to the activated carbon per g 4mg with SO ₂ conversion. This activated carbon was returned to the top of the reactor 2 of the cross flow type moving bed, and continuous operation was performed.

As a result of treating the exhaust gas under the above conditions, the desulfurization rate of the treated gas was 100%, the denitrification rate was 80%, and the ammonia leak in the treated gas was 2 ppm.

[0060] As a comparative example, was operated in the same manner as all the third embodiment but for the SO _X added after regeneration, the desulfurization rate was 100%, the denitration rate was 80%, the process gas The ammonia leak was 23 ppm.

[0061]

According to the present invention, since the carbonaceous catalyst is activated by NH _3, it has the effect of increasing the catalytic activity, and at the same time SO _X is added / adsorbed on the surface of the carbonaceous catalyst. Therefore, even if such a carbonaceous catalyst is returned to the reactor and the desulfurization and denitration treatment of the exhaust gas is performed again, ammonia is sufficiently captured by the carbonaceous catalyst, and ammonia is contained in the treated gas at the upper part of the reactor. There is no fear of leaks.

The method for treating exhaust gas of the present invention is particularly effective for preventing the leakage of annimmonia when the SO _X concentration in the exhaust gas is low.

[Brief description of drawings]

FIG. 1 shows an example of a treatment process of an exhaust gas containing SO _X and NO _X.

FIG. 2 shows an example in which the activity of a carbonaceous catalyst is further enhanced in a treatment process of an exhaust gas containing SO _X and NO _X.

FIG. 3 shows another example of the treatment process of the exhaust gas containing SO _X and NO _{X, in} which the activity of the carbonaceous catalyst is further enhanced.

[Explanation of symbols]

1 Exhaust Gas Introducing Line 2 Reactor 3 Ammonia Introducing Line 4 Carbonaceous Catalyst 5 Processing Gas Line 6, 106 Regenerator 7 Storage Area 8 Separation Area 9 Heat Exchange Area 10 Heat Transfer Tube 11 Heating Gas Introducing Line 12 Introducing Inert Gas Containing Ammonia Gas Area 13 Ammonia introduction line 14 Desorbed gas discharge line 15 Rectifier 16, 19, 20 Inert gas introduction line 17 Cooler 18 Cooling area 21 SO _X introduction line 22 SO _X adder 23 Oxygen-containing gas introduction line 24 SO _X addition Area 25, 27 Desorption gas introduction line 26 Catalyst pretreatment device

Claims (8)

[Claims] 1. Desulfurization and denitration treatment is performed in a cross-flow type moving bed reactor filled with a carbonaceous catalyst with or without injection of ammonia into exhaust gas containing sulfur oxides and nitrogen oxides, The carbonaceous catalyst inactivated in the reactor is regenerated with a moving bed regenerator, the carbonaceous catalyst is activated with ammonia, and the activated carbonaceous catalyst is again used as a carbonaceous catalyst for exhaust gas treatment. in the processing method of the exhaust gas utilized charged to the reactor, adding SO _X in the activated carbonaceous catalyst, a carbonaceous catalyst which said SO _X is added in the exhaust gas, characterized by utilizing the exhaust gas treating Processing method. 2. The method for treating exhaust gas according to claim 1, wherein SO _X is added in advance to the inactivated carbonaceous catalyst before being heated and regenerated by the regenerator. 3. The method of previously adding SO _X to the inactivated carbonaceous catalyst is a method of supplying SO _X by supplying an oxygen-containing gas or a gas containing oxygen and SO ₂ to the upper part of the regenerator. The method for treating exhaust gas according to claim 2, wherein: 4. The method of previously adding SO _X to the inactivated carbonaceous catalyst comprises the step of removing SO ₂ desorbed when the inactivated elementary catalyst is heated and regenerated in the presence of oxygen.
S by contacting with a deactivated carbonaceous catalyst
The method for treating exhaust gas according to claim 2 or 3, wherein O _X is added. 5. The method of pre-adding SO _X to the inactivated carbonaceous catalyst is a method of spraying concentrated sulfuric acid, dilute sulfuric acid, or an aqueous ammonium solution of sulfuric acid onto the inactivated carbonaceous catalyst to form SO _X. The method for treating exhaust gas according to claim 2, further comprising: 6. The method for adding SO _X to the activated carbonaceous catalyst is such that SO ₂ which is desorbed when the inactivated carbonaceous catalyst is heated and regenerated is activated in the presence of oxygen. The method for treating exhaust gas according to claim 1, 2, 3, 4, or 5, wherein SO _X is added by contacting with a carbonaceous catalyst. 7. The method for adding SO _X to the activated carbonaceous catalyst comprises spraying concentrated carbon dioxide or dilute sulfuric acid aqueous solution onto the activated carbonaceous catalyst to add SO _X.
The method for treating exhaust gas according to 3, 4, or 5. 8. The total amount of SO _X added to the carbonaceous catalyst used for treating the exhaust gas is 0.5 to 30 mg per g of carbonaceous catalyst in terms of SO _2. ,
The method for treating exhaust gas according to 5, 6 or 7.