JP2002370011A - Exhaust gas treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the powdering of a carbonaceous adsorbent in an exhaust gas treatment method wherein ammonia 50 is added to exhaust gas 30 containing a sulfur oxide and a nitrogen oxide and this exhaust gas is introduced into a moving bed type reaction column 10 filled with the carbonaceous adsorbent to be desulfurized and denitrated while the adsorbent discharged from the reaction column 10 is regenerated under heating in a regeneration column 20 to be again supplied to the reaction column 10. SOLUTION: The addition of ammonia is intermittently performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas treatment method for desulfurizing and denitrifying exhaust gas containing sulfur oxides and nitrogen oxides, and more particularly, to adding ammonia to the exhaust gas and filling it with a carbonaceous adsorbent. The present invention relates to an exhaust gas treatment method for performing desulfurization and denitration using a moving bed type reaction tower.

[0002]

2. Description of the Related Art As a method of treating various boiler exhaust gas or exhaust gas containing sulfur oxides and nitrogen oxides such as exhaust gas from a sintering furnace of a steel mill, desulfurization and denitration using a carbonaceous adsorbent such as activated carbon. There is a way to do the processing.

According to this method, an exhaust gas containing ammonia is introduced into a moving bed type reaction tower filled with a carbonaceous adsorbent, and the exhaust gas containing ammonia is passed through the adsorbent flowing down the moving bed in a cross flow. The exhaust gas is brought into contact with the adsorbent. Thus, the sulfur oxides are adsorbed and removed by the adsorbent, and the nitrogen oxides are reacted with ammonia by the catalytic function of the carbonaceous adsorbent, and are decomposed into nitrogen and water to be removed.

[0004] Since the carbonaceous adsorbent gradually reduces its catalytic function by adsorbing sulfur oxides, it is discharged from the lower part of the reaction tower and sent to a regeneration tower, where it is heated at a high temperature to regenerate it. A treatment is performed to release and regenerate sulfur oxides from the adsorbent.

At this time, since sulfur oxides are released from the adsorbent at a high concentration, the sulfur oxides can be used as a raw material for by-products such as sulfuric acid.

[0006] The regenerated carbonaceous adsorbent is discharged from the regeneration tower after cooling, and after removing fine powder that has been pulverized due to mechanical abrasion or the like, is supplied again to the upper part of the reaction tower to be recycled. However, the amount of the carbonaceous adsorbent is reduced by mechanical pulverization and chemical attrition, so that it is necessary to supply a new adsorbent.

The specific operating conditions of the above exhaust gas treatment method vary depending on the exhaust gas conditions and treatment targets (desulfurization rate, denitration rate, etc.).

For example, when the concentration of sulfur oxides contained in the exhaust gas is high and a high desulfurization rate and a high denitrification rate are required, two moving bed reactors are used, and the first reactor mainly uses After the desulfurization treatment is performed to reduce the concentration of sulfur oxides in the exhaust gas to about 100 ppm, ammonia is added to the exhaust gas, and the denitration treatment is mainly performed in the second reaction tower.

On the other hand, when the concentration of sulfur oxides contained in the exhaust gas is low (for example, 300 ppm or less) and it is not necessary to increase the denitration rate, it is uneconomical to use two reactors. Therefore, it is required to solve this.

As an example of such a processing method, Japanese Patent Publication No.
-54089, WO98 / 15340 and the like.

As a typical treatment method, an exhaust gas stream is divided into a plurality of exhaust gas streams, an ammonia-added exhaust gas stream is supplied to the upper part of the reaction tower, and an ammonia-free exhaust gas stream is added to the lower part of the reaction tower. There is a method of supplying.

The present inventors conducted tests of desulfurization and denitration under various conditions with reference to these techniques.
When the temperature of the exhaust gas was relatively low (for example, 100 ° C.), it was noticed that the carbonaceous adsorbent used was extremely powdered, and that this problem had to be separately solved.

[0013] The problem that the carbonaceous adsorbent powders is that the reaction between sulfur oxide and ammonia produces ammonium sulfate or acidic ammonium sulfate inside the adsorbent, which becomes solid and causes mechanical stress inside the adsorbent. Is generated, and thereby the adsorbent is destroyed. In the above exhaust gas treatment method, the powdered adsorbent is withdrawn from the treatment system, and a new adsorbent is replenished to the system by that amount, so that the operating cost increases.

[0014]

DISCLOSURE OF THE INVENTION The present inventors have made intensive studies to solve the above-mentioned problem of pulverization. First, the following experiment was performed.

EXPERIMENTAL EXAMPLE 1 An exhaust gas treatment experiment was carried out under the following conditions using a fixed bed type reaction tower filled with a carbonaceous adsorbent.

The exhaust gas conditions are as follows: exhaust gas temperature: 120 ° C. SO _X concentration: 220 ppm (dry base) NO _X concentration: 250 ppm (dry base) Oxygen concentration: 15.0 vol% (dry base) Water: 10.0 vol% ( (wet base).

The processing conditions are as follows: SV value: 400 h- ¹ gas passing time: 150 h NH ₃ addition amount: 546 ppm (dry base) equivalent.

The exhaust gas was continuously flowed through the fixed bed type reaction tower for 150 hours, and the desulfurization rate and the denitration rate were measured. Thereafter, the adsorbent was heated and regenerated at 500 ° C., and the exhaust gas was flowed again for 150 hours. As a result, the desulfurization rates during the first and second gas passages were 90% or more. The denitration rate was as shown in FIG.

In FIG. 1, the horizontal axis represents the gas passage time,
The vertical axis indicates the integrated average value of the denitration rate. By indicating the denitration rate as an integrated average value, the denitration rate when a moving bed type reaction tower is used can be immediately obtained.

For example, the denitration rate of 55% corresponding to a gas passing time of 150 hours is the denitration rate when the residence time of the carbonaceous adsorbent is 150 hours when the moving bed type reaction tower is used at the same SV value. Means 55%.

In the above experiment, the results of the desulfurization rate and the denitration rate were almost the expected values. Further, almost no ammonia was detected in the treated exhaust gas, and it was confirmed that there was no problem of leaked ammonia. However, as a result of examining the heat-regenerated carbonaceous adsorbent, remarkable pulverization was confirmed, and it was confirmed that this was a problem to be solved.

Experimental Example 2 In Experimental Example 1, the adsorbent after the second gas passage was heated and regenerated in the same manner, and the same exhaust gas was used to pass the gas without addition of ammonia. At that time, the desulfurization rate and the denitration rate were measured. As a result, the desulfurization rate during passing gas was 90% or more. The denitration rate at this time was as shown in FIG.

As described above, nitrogen oxides can be removed to some extent without adding ammonia to the exhaust gas. This is presumably because, when performing heat regeneration, if a large amount of ammonia or ammonium salt is contained in the adsorbent, a nitrogen functional group having denitration capability is bonded to the adsorbent.

In this case, since no ammonia is added,
As a matter of course, almost no ammonia is detected in the treated exhaust gas, and there is no problem of leaked ammonia.
Further, since ammonia is not added, no solid such as ammonium sulfate produced by reacting with ammonia is generated. Therefore, there is no problem of powdering the carbonaceous adsorbent.

For example, if there is no problem of pulverization in Experimental Example 1, such as when the exhaust gas temperature is high, a processing method combining Experimental Examples 1 and 2 can be considered.

For example, a method of dividing an exhaust gas stream into a plurality of exhaust gas streams, supplying an exhaust gas stream with added ammonia to a part of the reaction tower, and supplying an exhaust gas stream without adding ammonia to the other part of the reaction tower is considered. Can be

However, a method of increasing the exhaust gas temperature or a method of shortening the residence time of the adsorbent is not economical. Further, when the amount of ammonia added to the exhaust gas is reduced, the amount of powder is reduced, but at the same time, the denitration rate is significantly reduced. After all, there was no effective way to reduce powdering.

Therefore, the present inventors have tried to repeat the operation of Experimental Example 1 and the operation of Experimental Example 2 at regular time intervals as an alternative method. That is, the addition of ammonia to the exhaust gas is not performed continuously, but is performed intermittently.

In this case, regarding the pulverization of the carbonaceous adsorbent, although there was no material to be expected at all before the experiment, it is expected that the effect of Experimental Example 2 which does not cause pulverization can be reflected at all. Was. In addition, it was expected that the denitration rate would be an intermediate value between Experimental Examples 1 and 2.

Experimental Example 3 Under the same conditions as in Experimental Example 1, ammonia was added intermittently every 30 minutes. That is, ammonia was not added at all for 30 minutes, and ammonia was added for the next 30 minutes, and this was repeated alternately. However, in order to make the total amount of ammonia the same as that in Experimental Example 1, twice the amount of ammonia (equivalent to 1092 ppm) in Experimental Example 1 was added during the addition.

As a result, the desulfurization rate at the time of passing gas was 90%.
That was all. Further, as shown in FIG. 3, although the denitration rate was somewhat inferior to the result shown in FIG. 1, almost the same, better-than-expected good results were obtained.

Further, almost no ammonia was detected in the treated exhaust gas, and it was confirmed that there was no problem of leaked ammonia.

As a result of examining the pulverization of the heat-regenerated carbonaceous adsorbent, it was confirmed that the carbon adsorbent was significantly reduced as compared with the case of Experimental Example 1.

EXPERIMENTAL EXAMPLE 4 The treatment was carried out under the same conditions as in Experimental Example 3 except that the amount of added ammonia was half that of Experimental Example 3 (corresponding to 546 ppm when added).

As a result, almost the same results as in Experimental Example 3 were obtained. That is, powdering was significantly reduced, and the denitration rate was satisfactory as shown in FIG.

From the results of Experimental Examples 3 and 4, it was confirmed that when the addition of ammonia to the exhaust gas was performed intermittently, powdering of the carbonaceous adsorbent was significantly suppressed.

Therefore, the fineness of the amount of powder under various conditions was measured finely to elucidate the mechanism of the suppression of powdering, and repeated studies for practical use were made.

Experimental Example 5 By sieving the carbonaceous adsorbent with a low tap,
The column was filled with 50 cc having a particle size of 3 to 5.66 mm, and gas was passed for a predetermined time.

The adsorbent after the treatment is heated and regenerated at 500 ° C.
This was sieved with a low tap and the ratio of the particle size to 2 mm or less and 1 mm or less was determined as the powdering rate.

The conditions for passing gas were as follows. Exhaust gas temperature: 120 ° C. SO _X concentration: 220 ppm (dry base) Oxygen concentration: 15.0% by volume (dry base) Moisture: 10.0 volume% (wet base) Processing conditions SV value: 3200 h- ¹ gas passing time: 20 h NH ₃ addition amount: NH ₃ / SO _X ratio = 0.5, 1.0, 1.
5, 2.0 (on a molar basis) As shown in FIG. 5, as the NH ₃ / SO _X ratio is increased,
It was confirmed that the powdering ratio increased.

Experimental Example 6 Under the conditions of Experimental Example 5, gas was passed first for 24 hours without adding ammonia. Thereafter, ammonia was added under the same conditions as in Experimental Example 5 to determine the powdering rate. FIG.
As shown in Table _2, even when the NH ₃ / SO _X ratio was increased, the powdering ratio did not increase so much, and it was confirmed that the ratio was significantly better than that in Experimental Example 5.

From the results of Experimental Examples 5 and 6, it was clarified that the carbonaceous adsorbent which had previously absorbed sulfur oxides was significantly suppressed from powdering.

The reason can be inferred as follows.

1) When both sulfur oxides and water are adsorbed by the adsorbent, the water tends to liquefy near the surface of the adsorbent particles. On the other hand, since the sulfur oxide has low solubility in water, it is not absorbed near the surface of the adsorbent particles, but is adsorbed on the whole particles by internal pores extending to the center of the particles.

2) The sulfur oxide is oxidized into sulfuric acid in the pores in the particles. Since the generated sulfuric acid has high water absorption,
The moisture adsorbed on the particle surface also penetrates into the internal pores of the particle.

3) When both ammonia and water are adsorbed by the adsorbent, the solubility of ammonia in water is high, so that ammonia water is generated near the surface of the adsorbent, and ammonia does not reach the internal pores. Can not.

4) When sulfur oxides and ammonia are adsorbed on the adsorbent together with water, the sulfur oxides dissolve in the ammonia water generated near the surface of the adsorbent, so that the sulfur oxides reach the internal pores. Can not. As a result, acidic ammonium sulfate or ammonium sulfate is generated near the surface of the adsorbent.

5) When sulfur oxide and ammonia are adsorbed together with water on the carbonaceous adsorbent which has previously absorbed sulfur oxide, the adsorbed water is sucked by the sulfuric acid in the internal pores. As a result, ammonia also reaches the internal pores. As a result, acidic ammonium sulfate or ammonium sulfate is generated on average in the internal pores of the adsorbent, so that powdering of the adsorbent concentrated near the surface of the adsorbent is suppressed.

The present invention has been completed based on the results of the above experiments and includes the following technical contents.

1) When the adsorbent is heated and regenerated, a nitrogen functional group having a denitration ability is bonded to the adsorbent by including ammonia or an ammonium salt.

2) Denitration treatment is performed without adding ammonia to exhaust gas by utilizing the denitration ability of the nitrogen functional group.

3) To produce sulfuric acid in the carbonaceous adsorbent by performing a denitration treatment without adding ammonia to the exhaust gas.

4) Denitration treatment in which ammonia is added to exhaust gas. In this case, by the action of sulfuric acid generated on the carbonaceous adsorbent. Suppress powdering of the adsorbent.

Accordingly, it is an object of the present invention to provide a method for treating exhaust gas in which desulfurization and denitration of exhaust gas at a relatively low temperature are prevented from powdering the adsorbent.

[0055]

The present invention to achieve the above object is as described below.

[1] Ammonia is added to an exhaust gas containing sulfur oxides and nitrogen oxides, and the mixture is introduced into a moving bed type reaction tower filled with a carbonaceous adsorbent to perform desulfurization and denitration treatment. An exhaust gas treatment method for heating and regenerating an adsorbent discharged from a reactor and then supplying the adsorbent to the reaction tower again, wherein ammonia is intermittently added.

[2] While dividing the reaction tower into a plurality of parts, the exhaust gas stream is divided and introduced into each reaction tower, and ammonia is intermittently added to at least one exhaust gas stream. An exhaust gas treatment method according to item 1.

[3] The exhaust gas treatment method according to [1] or [2], wherein the temperature of the exhaust gas introduced into the moving bed type reaction tower is 80 to 140 ° C.

[4] The amount of ammonia added to the exhaust gas is 0.1 in the molar ratio (ammonia / sulfuric acid) of ammonia and sulfuric acid (both containing salts) contained in the carbonaceous adsorbent to be regenerated in the regenerator. 3 to 1.5 [1] to [3]
An exhaust gas treatment method according to any one of the above.

[0060]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The exhaust gas treatment apparatus used in the present invention and the operating conditions of the exhaust gas are almost the same as the conventionally known exhaust gas treatment apparatus using a carbonaceous adsorbent and ammonia and the operating conditions thereof. In that the addition of is intermittent.

The exhaust gas to be treated in the present invention is not particularly limited, but preferably has a sulfur oxide concentration of 50 to 300 ppm, more preferably 100 to 250 ppm. The sulfur oxide is a so-called SOx such as SO ₂ and SO ₃ . As the nitrogen oxide, NO, is a so-called NOx such as NO _2. Nitrogen oxide concentration is 50-300p
pm is preferable, and 100 to 250 ppm is more preferable.

The temperature of the exhaust gas to be treated in the present invention is not particularly limited, but from the viewpoint of the object of the present invention for preventing powdering of the carbonaceous adsorbent, the temperature is preferably from 80 to 140 ° C., particularly preferably from 90 to 130 ° C. C is preferred.

In the present invention, as a specific method of treating exhaust gas, it is fundamental to intermittently add ammonia to the exhaust gas. That is, addition and non-addition of ammonia are performed alternately. The switching time between addition and non-addition can be determined as appropriate.

The effect of suppressing pulverization due to no addition of ammonia is exhibited even in a short time (for example, 1 minute). Conversely, when the time is long (for example, 10 hours or more), there is no problem of inhibiting the pulverization suppression effect, but the change in the denitration rate when switching between addition and non-addition may become significant. is there. Although it depends on the operating conditions, the addition time is preferably 1 minute to 10 hours, more preferably 10 minutes to 2 hours, from the practical point of view such as operability. The non-addition time is preferably 1 minute to 10 hours, more preferably 10 minutes to 2 hours.

The amount of ammonia to be added can be considered in the same manner as in conventional continuous addition. That is, it is added so that the molar ratio (ammonia / sulfuric acid) of ammonia and sulfuric acid (both containing salts) contained in the carbonaceous adsorbent to be regenerated in the regenerator is 0.3 to 1.5. preferable.

The molar ratio is preferably high in terms of denitration performance, and is preferably low when it is necessary to suppress the amount of ammonia generated in the regeneration tower. When the molar ratio is too low, the amount of carbon consumed in the reduction reaction of sulfuric acid increases, and the strength of the adsorbent may decrease. Therefore, the molar ratio is preferably 0.3 or more.

The carbonaceous adsorbent used in the present invention is preferably activated carbon or activated coke.

The operating temperature of the regeneration tower is 450 to 550
C is preferred.

Hereinafter, embodiments of the present invention will be described in detail.

[0070]

Embodiment 1 FIG. 7 is a process diagram showing an example of an exhaust gas treatment apparatus used for carrying out the present invention.

The moving bed type reaction tower 10 is filled with a carbonaceous adsorbent to form a moving bed which moves downward from above. The adsorbent extracted from the lower part of the reaction tower 10 is sent to the regeneration tower 20 by the line 60 and is heated and regenerated. The regenerated adsorbent is returned to the upper part of the reaction tower 10 by the line 70.

On the other hand, an exhaust gas containing sulfur oxides and nitrogen oxides is supplied to the reaction tower 10 from a line 30.
In the reaction tower 10, after the exhaust gas passes through the moving bed of the adsorbent in the horizontal direction, the treated gas is discharged through the line 40. Ammonia is added to the exhaust gas line 30 from a line 50.

A feature of the present invention is that the addition of ammonia is performed not intermittently but intermittently. That is,
The addition and non-addition of ammonia are performed alternately. As described above, the switching time between addition and non-addition and the amount of added ammonia are appropriately determined according to the processing amount of the apparatus, the state of the processing target, the removal level of sulfur oxides and nitrogen oxides, and the like.

In the drawing, a line 80 indicates a line for discharging high-concentration sulfur oxides generated by regeneration of the adsorbent.

Hereinafter, the operating conditions of the above-mentioned exhaust gas treatment apparatus and the obtained exhaust gas treatment results will be described.

(Operating conditions) Exhaust gas amount: 1500 Nm ³ / h Exhaust gas temperature: 125 ° C. SOx concentration: 180 ppm (dry base) NOx concentration: 180 ppm (dry base) Oxygen concentration: 15 vol% (dry base) Moisture: 13 vol% (Wet base) Adsorbent, particle size: activated coke, 9 mmφ Reaction tower type: Moving bed type Reaction tower SV value: 400 h ^-1 Adsorbent residence time: 150 hours NH ₃ addition time: 30 minutes NH ₃ non-addition time: 30 Minute NH ₃ addition amount: 470 ppm (dry base) (at the time of addition) NH ₃ / SOx ratio: about 1.0 (reaction tower outlet) Regeneration tower heating temperature: 500 ° C. Regeneration tower heating time: 3 hours (result) Desulfurization rate: 99% or more Denitration rate: 40% or more Powdering rate: 1 to 1.5% (including those mechanically powdered) Example 2 FIG. It is a process diagram showing another example of exhaust gas treating apparatus used for the implementation.

The moving bed type reaction tower comprises a first reaction tower 11 and a second reaction tower 12. As described above, the tower may be provided separately, but one reaction tower may be vertically divided into two sections to form a first moving bed and a second moving bed.

The adsorbent of the reaction towers 11 and 12 is supplied to the line 6
It is extracted at 1 and 62 and sent to the regeneration tower 20 by the line 60 at a time to be heated and regenerated. The regenerated adsorbent is withdrawn from the regenerator via line 70 and
And 72 return to the top of the reaction towers 11 and 12.

Therefore, in the reaction towers 11 and 12, the adsorbent forms a moving bed that descends from top to bottom.

On the other hand, the exhaust gas containing the sulfur oxides and the nitrogen oxides is supplied to the reaction towers 11 and 12 by the lines 31 and 32 divided from the line 30. Reaction tower 1
In 1 and 12, the exhaust gas passes through the moving bed of the adsorbent in the horizontal direction and is then discharged by the lines 41 and 42,
They merge and are discharged at line 40.

The exhaust gas lines 31 and 32 have a line 5
Ammonia is added from 1 and 52.

A feature of the present invention is that the addition of ammonia is performed not intermittently but intermittently. That is,
The addition and non-addition of ammonia are performed alternately. The addition and the non-addition may be performed separately in each reaction column, or in relation to each other, for example, the reaction column 12 is not added when the reaction column 11 is added, and the reaction is performed when the reaction column 11 is not added. Column 12 can also be added.

Alternatively, the addition of ammonia may be intermittently performed only in one of the reaction towers, and the ammonia may not be added in the other reaction tower.

As described above, the time for switching between addition and non-addition and the amount of ammonia added can be determined as appropriate.

In this example, the reaction tower or the moving bed partitioned was 2
Although the number is shown, three or more pieces can be used. Further, it is not necessary to add ammonia to all the exhaust gas supply lines, and an unadded exhaust gas line may be provided.

Embodiment 3 FIG. 9 is a process diagram showing still another example of an exhaust gas treatment apparatus used for carrying out the present invention.

The moving bed type reaction tower is constituted by connecting a first reaction tower 11 and a second reaction tower 12 in series. As described above, the tower may be provided separately, but one reaction tower may be divided into upper and lower two sections.

The adsorbent extracted from the lower part of the reaction tower 11 is supplied to the upper part of the reaction tower 12. The adsorbent extracted from the lower part of the reaction tower 12 is sent to the regeneration tower 20 by a line 60 and is heated and regenerated.

The regenerated adsorbent is returned to the upper part of the reaction tower 11 by the line 70. Therefore, the reaction towers 11 and 1
In 2, the adsorbent forms a moving bed that descends from top to bottom.

On the other hand, the exhaust gas containing the sulfur oxides and the nitrogen oxides is supplied to the reaction towers 11 and 12 by the lines 31 and 32 divided from the line 30.

In the reaction towers 11 and 12, the exhaust gas passes through the moving bed of the adsorbent in the horizontal direction, is discharged by the lines 41 and 42, merges and is discharged by the line 49.

The exhaust gas lines 31 and 32 have a line 5
Ammonia is added from 1 and 52.

A feature of the present invention is that the addition of ammonia is performed not intermittently but intermittently. That is,
The addition and non-addition of ammonia are performed alternately. The addition and the non-addition may be performed separately in each reaction column, or in relation to each other, for example, the reaction column 12 is not added when the reaction column 11 is added, and the reaction is performed when the reaction column 11 is not added. Column 12 can be added.

As described above, the switching time between addition and non-addition, and the amount of added ammonia can be determined as appropriate.

In this example, the reaction tower or the partitioned moving bed is 2
Although the number is shown, three or more pieces may be used.

Further, it is not necessary to add ammonia to all exhaust gas supply lines, and it is also possible to provide a non-added exhaust gas line.

Further, if the upper moving bed is once subjected to an intermittent addition or non-addition treatment of ammonia, it is possible to continuously add ammonia to the lower moving bed. .

This is because the carbonaceous adsorbent descending the moving bed has undergone the process of non-addition of ammonia before being subjected to intermittent addition of ammonia, and thus has the effect of suppressing pulverization. It is because it becomes.

[0099]

According to the present invention, in an exhaust gas treatment method in which ammonia is added to an exhaust gas containing sulfur oxides and nitrogen oxides, and this is subjected to desulfurization and denitrification treatment with a carbonaceous adsorbent, the addition of ammonia is intermittent. I decided to do it in
Powdering of the carbonaceous adsorbent can be reduced. Therefore, according to the method of the present invention, the amount of carbonaceous adsorbent to be replenished is reduced, and the operating cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between an integrated average denitration rate and a gas passage time when exhaust gas treatment is performed by continuously adding ammonia.

FIG. 2 After exhaust gas treatment by adding ammonia,
It is a graph which shows the relationship between an integrated average denitration rate and gas passage time when exhaust gas processing is performed without adding ammonia.

FIG. 3 is a graph showing the relationship between the integrated average denitration rate and the gas passage time when exhaust gas treatment is performed by adding ammonia intermittently every 30 minutes.

4 is a graph showing the relationship between the integrated average denitration rate and the gas passage time when the addition of ammonia is halved from that in FIG.

FIG. 5 is a graph showing the relationship between the ratio of NH ₃ and SO ₂ and the powdering rate when exhaust gas treatment is performed by continuously adding ammonia.

FIG. 6 is a graph showing the relationship between the ratio of NH ₃ and SO ₂ and the powdering rate when exhaust gas treatment is performed without adding ammonia first and then ammonia is added to perform exhaust gas treatment. is there.

FIG. 7 is a process chart showing an example of an exhaust gas treatment apparatus used for carrying out the present invention.

FIG. 8 is a process chart showing another example of an exhaust gas treatment apparatus used for carrying out the present invention.

FIG. 9 is a process chart showing still another example of the exhaust gas treatment apparatus used for carrying out the present invention.

[Explanation of symbols]

Reference Signs List 10 moving bed reaction tower 11 first reaction tower 12 second reaction tower 20 regeneration tower 30, 31, 32, 40, 41, 42, 50, 51, 5
2, 60, 61, 62, 70, 71, 72, 80 lines

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor: Shigeyoshi Nakano 1-3-3 Hibikicho, Wakamatsu-ku, Kitakyushu-shi, Fukuoka Inside the Research Laboratory of Mitsui Mining Co., Ltd. F-term in the Tochigi Plant (reference) 4D002 AA02 AA12 AC01 AC02 BA04 BA06 CA08 DA07 DA41 EA07 EA08 GA01 GB03 GB08 HA01

Claims (4)

[Claims] Claims 1. An ammonia is added to an exhaust gas containing a sulfur oxide and a nitrogen oxide, and the ammonia is introduced into a moving bed type reaction tower filled with a carbonaceous adsorbent to perform desulfurization and denitration treatments.
An exhaust gas treatment method for heating and regenerating an adsorbent discharged from a reaction tower and then supplying the adsorbent to the reaction tower again, wherein ammonia is intermittently added. 2. The method according to claim 1, wherein the reaction tower is divided into a plurality of parts, the exhaust gas stream is divided and introduced into each of the reaction towers, and ammonia is added intermittently to at least one exhaust gas stream. An exhaust gas treatment method as described above. 3. The exhaust gas treatment method according to claim 1, wherein the temperature of the exhaust gas introduced into the moving bed type reaction tower is 80 to 140 ° C. 4. The amount of ammonia added to the exhaust gas is:
The molar ratio of ammonia and sulfuric acid (both containing salts) contained in the carbonaceous adsorbent to be regenerated in the regeneration tower (ammonia /
The method for treating exhaust gas according to any one of claims 1 to 3, wherein the sulfuric acid is 0.3 to 1.5.