JPH08155300A - Dry denitration of sulfur oxide-containing low temperature exhaust gas and desulfurizing-denitrating catalyst - Google Patents

Abstract

PURPOSE: To inexpensively desulfurize and denitrate sulfur oxide-containing low temp. exhaust gas with high efficiency and to facilitate the regeneration treatment of a manganese ore used in desulfurization. CONSTITUTION: In the first manganese ore moving bed 3 among two manganese ore moving beds 3, 4 arranged in series with respect to the flow of exhaust gas A, a manganese ore B is used as a catalyst not only to oxidize sulfur dioxide in an exhaust gas B' to sulfur trioxide but also to highly remove sulfur oxides as ammonium sulfate by ammonia D. At the same time, a part of nitrogen oxide is also removed by ammonia catalytic reducing denitration using the manganese ore B as a catalyst. Thereafter, in the second manganese ore moving bed 4, a manganese ore C is used as a catalyst to reduce nitrogen oxides in an exhaust gas A" to nitrogen using unreacted ammonia of the manganese ore moving bed 3 as a reducing agent. The mangannese ore B' used in the removal of sulfur oxides is washed to remove bonded ammonium sulfate and circulated to be reused in the removal of sulfur oxides.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sulfur oxide-containing low-temperature exhaust gas dry denitration method for removing or reducing nitrogen oxides from low-temperature exhaust gas containing sulfur oxides generated in a sintering machine of an iron mill, for example. The present invention relates to a desulfurization / denitration catalyst.

[0002]

2. Description of the Related Art As a dry-type exhaust gas desulfurization method using metal oxides, "flue gas desulfurization" (Industrial Pollution Control Association, 197)
(3 years) Pages 55 to 66 indicate that sulfur dioxide is immobilized and removed as sulfite and sulfate by the reaction of metal oxide and sulfur dioxide. For example, in the case of a divalent metal oxide, the reaction is represented by the equation (1). It is described that manganese oxide is a metal oxide effective for removing sulfur dioxide by the reaction of the formula (1). In addition, "Chemical Engineering"
Progress Vol. 66, No. 1, P. 61
(1970) "absorbs and removes sulfur dioxide in the exhaust gas by using powdered active manganese oxide as an absorbent, and the reaction product manganese sulfate is dissolved in water and sent to a regeneration process to supply ammonia and pressurized air. A method of regenerating the absorbent by blowing and oxidizing is described.

[0003]

[Equation 1] MeO + SO ₂ → MeSO ₃ (1) where Me: metal

Generally, for removing nitrogen oxides in exhaust gas,
As shown in page 5, line 253, "Catalyst Lecture" Vol. 7 (Catalyst Society), V ₂ as an ammonia reduction denitration catalyst was used.
O ₅ -TiO ₂ catalyst has been used. As a method of using an iron-making raw material, there is also a method of using iron ore as a denitration catalyst as disclosed in JP-A-57-15824. Further, as seen in JP-A-51-62181, manganese dioxide is known to be highly active as a denitration catalyst at low temperatures.

As a method for removing or reducing nitrogen oxides from low-temperature exhaust gas containing sulfur oxides generated from a sintering machine of a steel mill, "fuel conversion and SOx / NOx countermeasure technology" (Project News Co .; Junpei Ando) Pp. 199, as shown in FIG. 10-6, about 100 to 150 ° C.
The low-temperature flue gas is first subjected to electrostatic collection, then desulfurized by wet desulfurization using the limestone-gypsum method, further purified by a wet electrostatic precipitator, and then heated to 400 ° C by a gas-gas heat exchanger and a heating furnace to form a granular catalyst. There is a method of performing ammonia reduction denitration with.

[0006]

The method of removing sulfur dioxide in exhaust gas using the above metal oxide has a limit in the amount of treatment because the metal oxide itself is reacted with sulfur dioxide, and there is a problem in service life. It was The above-mentioned regenerating method has a drawback that it requires a regenerating device and the process is complicated.

Since the above method uses vanadium, there is a problem that the catalyst is very expensive. Further, in the above method, the reaction temperature was 300 to 370 ° C., and heating was necessary to denitrate low temperature exhaust gas of 150 ° C. or lower such as iron plant sintering exhaust gas. Further, the above method has a problem that the catalyst is expensive as in the above method.

The above method is very expensive because it requires a high degree of pretreatment for denitration.

According to the present invention, in removing nitrogen oxides in low-temperature exhaust gas containing sulfur oxides, inexpensive and highly efficient desulfurization and denitration are performed at exhaust gas temperature, and the manganese ore used for desulfurization can be easily regenerated. And a desulfurization / denitration catalyst.

[0010]

The summary of the present invention is as follows.

Manganese dioxide 30 wt% or more 80
wt% or less, aluminum oxide 5 wt% or more 15 wt
% Or less of a manganese ore containing catalyst for desulfurization / denitration.

The catalyst for desulfurization / denitration according to claim 1, which is composed of manganese ore containing 5 wt% or more and 10 wt% or less of bound water and heat-treated at 400 ° C. or more and 600 ° C. or less.

In removing nitrogen oxides in exhaust gas containing sulfur dioxide, manganese ore is used as a catalyst to oxidize sulfur dioxide in sulfur oxides in exhaust gas to sulfur trioxide, and ammonia is used to remove sulfur oxides as ammonium sulfate. At the same time, a low-temperature exhaust gas dry denitration method containing sulfur oxides, characterized in that manganese ore is used as a catalyst and ammonia is used as a reducing agent to reduce and remove nitrogen oxides in the exhaust gas.

In removing nitrogen oxides in exhaust gas containing sulfur dioxide, manganese ore is used as a catalyst to oxidize sulfur dioxide in sulfur oxides in exhaust gas to sulfur trioxide, and ammonia is used to remove sulfur oxides as ammonium sulfate. After that, a low-temperature exhaust gas dry denitration method containing sulfur oxides, characterized in that nitrogen oxide in the exhaust gas is reduced and removed using manganese ore as a catalyst and ammonia as a reducing agent.

To remove nitrogen oxides in the exhaust gas containing sulfur dioxide, two reactors of manganese ore are provided in series with the flow of the exhaust gas, of which the first reactor uses manganese ore as a catalyst. After oxidizing the sulfur dioxide in the sulfur oxides in the exhaust gas to sulfur trioxide and removing the sulfur oxides as ammonium sulfate with ammonia, the manganese ore is used as a catalyst in the second reactor and the ammonia is used as a reducing agent in the exhaust gas. A low-temperature exhaust gas dry denitration method containing sulfur oxides, characterized by reducing and removing nitrogen oxides therein.

In the sulfur oxide-containing low temperature exhaust gas dry denitration method according to any one of the above, the manganese ore used for sulfur oxide removal is washed with water to remove ammonium sulfate adhering to the manganese ore, and then the manganese ore is circulated. A low-temperature exhaust gas dry denitration method containing sulfur oxide, characterized by being reused for removing sulfur oxide.

The low-temperature exhaust gas dry denitration method containing sulfur oxides according to any one of the above 1 to 3, wherein sulfur oxides and nitrogen oxides in exhaust gas are removed using the desulfurization / denitration catalyst. .

[0018]

In order to solve the above-mentioned problems, the present invention has clarified the component composition of manganese ore having an excellent catalytic function at low temperatures and further improved the activity. Manganese ore exerts an excellent denitration catalytic function by using ammonia as a reducing agent under exhaust gas conditions containing no sulfur oxide,
Under sulfur oxide-containing exhaust gas conditions, sulfur dioxide is oxidized to sulfur trioxide by the oxidation catalytic action of manganese ore, and ammonium sulfate is produced by the reaction of this sulfur trioxide with ammonia and water. Since this ammonium sulfate formation has a faster reaction rate than the reduction of nitrogen oxides with ammonia,
There has been a problem that ammonium sulfate adheres to the surface of manganese ore and the denitration catalytic function deteriorates. However, if sulfur oxide is fixed as ammonium sulfate by utilizing this reaction, desulfurization becomes possible. Further, when the manganese ore to which ammonium sulfate is attached is washed with water, both the denitration performance and the desulfurization performance are recovered, and the desulfurization performance is recovered better than the denitration performance. Therefore, by utilizing this, it became possible to efficiently remove nitrogen oxides from the low-temperature exhaust gas containing sulfur oxides, which uses manganese ore as a denitration catalyst. In other words, by using manganese ore containing manganese dioxide as a sulfur dioxide oxidation catalyst in the reaction layer filled with manganese ore, the sulfur dioxide is selectively oxidized on the surface of manganese dioxide by the oxidation reaction with oxygen in the exhaust gas. Is oxidized to sulfur trioxide. Then, sulfur trioxide is fixed as ammonium sulfate by a reaction between water in the exhaust gas and ammonia added from the outside, and sulfur oxides are removed from the exhaust gas. Furthermore, nitrogen oxides are reduced and denitrated by the denitration catalytic action of manganese ore using ammonia as a reducing agent. The manganese ore with the ammonium sulfate immobilized on the surface is extracted from the layer and washed with water to dissolve the ammonium sulfate in water to release it from the surface of the manganese ore, and the function of the manganese ore as a catalyst is regenerated and reused in circulation. Further, advanced desulfurization can be performed by performing advanced desulfurization in the first stage, and by performing ammonia reduction denitration with a gas containing almost no sulfur oxide in the latter stage using manganese ore as a catalyst. High-level desulfurization can be performed by wet desulfurization such as the conventional lime-gypsum method or dry desulfurization using activated coke, but if these desulfurizations are newly added, the equipment becomes complicated and expensive. Also, the use of manganese ore for desulfurization simplifies the process.

The present invention will be described in detail below with reference to the drawings. FIG. 1 shows an example of the flow of the method of the present invention.

The exhaust gas A discharged from the sintering machine 1 is removed by the electrostatic precipitator 2 to a dust concentration of 100 mg / Nm ³ or less, preferably 50 mg / Nm ³ or less. The flue gas A ′ after dust removal is introduced into the manganese ore moving layer 3 and comes into contact with the manganese ore B and the ammonia D introduced from outside in the moving layer 3, and the sulfur dioxide in the flue gas is converted into the manganese ore in the manganese ore B. Oxygen in the exhaust gas A ′ is oxidized to sulfur trioxide by the oxidation catalyst action ((2) Formula 2), and then sulfur trioxide reacts with water in the exhaust gas A ′ and ammonia D added from the outside (( 3) It is immobilized and removed as ammonium sulfate [(NH ₄ ) ₂ SO ₄ ] by the formula 3). In addition, nitrogen oxides are reduced and removed using ammonia D as a reducing agent by the denitration catalytic action of manganese ore B ((4) Formula 4)
The exhaust gas A ″ is released to the atmosphere. From the above, desulfurization and denitration can be performed simultaneously.

[0021]

[Equation 2] SO ₂ + (1/2) O ₂ → SO ₃ (2)

[0022]

[Equation 3] 2NH ₃ + SO ₃ + H ₂ O → (NH ₄ ) ₂ SO ₄ (3)

[0023]

[Formula 4] 4NO + 4NH ₃ + O ₂ → 4N ₂ + 6H ₂ O (4)

The manganese ore B'having the sulfur oxides fixed on the surface of the ore as ammonium sulfate is extracted, and the ammonium sulfate is dissolved in water by the washing facility 5 to remove dust and ammonium sulfate E, and the washed manganese ore B'is removed. 'Is recycled in the manganese ore moving bed 3.

The manganese ore moving bed is shown in FIG.
When separated into two parts, the denitration performance can be further improved with the same moving bed volume. That is, the moving speed of manganese ore in the first manganese ore moving layer 3 is adjusted to a speed at which sulfur oxides can be completely immobilized and removed, and high desulfurization and partial ammonia catalytic reduction denitration are performed in the manganese ore moving layer 3. The exhaust gas A ″ from which sulfur oxides have been highly removed is introduced into the denitration manganese ore moving layer 4, and the unreacted ammonia and manganese ore C in the manganese ore moving layer 3 are transferred in the moving layer 4.
In contact with, the ammonia catalytic reduction denitration (Equation (4)) is performed by the denitration catalytic action of manganese dioxide in the manganese ore C, nitrogen oxides are removed, and the exhaust gas A ″ ′ is released to the atmosphere. In the manganese ore moving layer 3, manganese ore B'having sulfur oxides fixed as ammonium sulfate on the surface of the ore is extracted, and ammonium sulfate is dissolved in water by a water washing facility 5 to remove dust and ammonium sulfate E, and manganese after water washing is performed. The ore B ″ is recycled and reused in the manganese ore moving bed 3. When the dust cannot be completely removed by the electric dust collector 2 and the manganese ore moving layer 3, the manganese ore is extracted in order to prevent the increase in the pressure loss of the manganese ore moving layer 4 due to the dust. The extracted manganese ore C'has no ammonium sulphate adhering, so washing and regeneration is not necessary, and the dust F is separated by the sieve 6, and the manganese ore C '' from which the dust is separated is reused by circulation in the manganese ore moving layer 4. To be done. Further, in the case of an iron mill, it is possible to mix the dust from the extracted manganese ore C ′ and mix it with the sintering raw material as a manganese source of pig iron for use. In this case, the manganese ore moving layer 4 may be supplemented with new manganese ore. When there is no dust in the exhaust gas A ″ flowing into the moving bed 4, a fixed bed may be used instead of the moving bed 4.

The dust removing device may be any device other than the electric dust collector as long as it can remove dust to a predetermined dust content, for example, a cyclone,
Bag filters, moving bed dust removers, etc. can be adopted.

The temperature of the exhaust gas introduced into the manganese ore moving bed is about the temperature of the sintering exhaust gas, that is, 90 ° C. or higher and 150 ° C.
It may be the following, but it is preferably 120 ° C. or higher for efficient desulfurization and denitration. Further, the concentrations of sulfur oxides and nitrogen oxides in the exhaust gas are not limited because the moving bed capacity and the moving amount may be determined according to the concentration and the gas amount.

The manganese ore used has a manganese dioxide content of 30 wt% or more and 80 wt% or less, preferably 5 wt% or less.
A catalyst having a content of 0 wt% or more and 70 wt% or less and an aluminum oxide content of 5 wt% or more and 15 wt% or less is suitable as a catalyst. Although aluminum oxide alone has low oxidation catalytic activity and denitration catalytic activity, it can act as a cocatalyst for manganese dioxide and improve the oxidation catalytic activity and denitration catalytic activity of manganese dioxide. When manganese dioxide and aluminum oxide are present in the above-mentioned respective contents, the performance is remarkably improved. As shown in FIGS. 3 and 4, when the content of manganese dioxide is less than 30 wt%, or the content of aluminum oxide is less than 5 wt%, desulfurization and
The denitration catalytic activity is not sufficient. The higher the manganese dioxide content, the higher the activity, but the manganese dioxide content is 80
High-quality manganese ores with higher than wt% have a low yield and are expensive, and are economically difficult to use. Realistically, the content of manganese dioxide, which is rich in production, is 50 wt.
% Or more and 80 wt% or less is preferably used. For the manganese dioxide content, the amount of active oxygen is determined by the sodium oxalate decomposition potassium permanganate titration method (JIS-M8233 Active oxygen determination method in manganese ore), and the manganese dioxide content is obtained by using the conversion formula of Equation 5. .

[0029]

## EQU00005 ## Manganese dioxide = active oxygen × 5.434

The aluminum oxide content is 5 wt%
If it is 15 wt% or more and above, it contributes to the activity improvement, but 1
If it exceeds 5 wt%, the ore becomes brittle and the powdering ratio becomes large, and the strength is not sufficient in actual use and it cannot be used. The aluminum oxide content is determined by the EDTA titration method (JI
S-M8239 aluminum oxide in manganese ore).

As shown in FIGS. 5 and 6, 5 wt% of bound water is used.
% Or more and 10 wt% or less 400 manganese ore containing
The performance is further improved by using a manganese ore whose heat treatment is carried out at a temperature of not lower than 600 ° C. and not higher than 600 ° C. and which has an improved specific surface area. The bound water content may be 5 wt% or more and 10 wt% or less, and if it exceeds 10 wt%, it becomes brittle due to heat treatment and lacks strength, so that it cannot be practically used. Here, the bound water is
It refers to water that has penetrated into crystallization water in ores and manganese ores and cannot be easily removed at 100 ° C., which is the boiling point of water at 760 mmHg. The combined water content is determined by the gravimetric method (JIS-
M8231 Method for determining combined water in manganese ore). Further, the specific surface area is improved at a heat treatment temperature of 400 ° C. or higher, but if it exceeds 600 ° C., the specific surface area is changed due to the transition of manganese dioxide to dimanganese trioxide (Mn ₂ O ₃ ).
Both catalytic activity decreases. The increase of the specific surface area is mainly due to the desorption of bound water due to heat, and therefore the heating atmosphere is not particularly limited. The manganese ore size is preferably 3 to 20 mm, particularly preferably 5 to 10 mm, from the viewpoint of desulfurization / denitration efficiency.

In the following examples, the manganese dioxide content, aluminum oxide content and bound water content were measured by the above-mentioned methods. However, even if it does not depend on the above-mentioned method, any method may be used as long as it is possible to obtain almost the same measurement result.

The main components of manganese ore other than manganese dioxide, aluminum oxide and bound water are iron oxides (FeO, F).
e ₂ O ₃ ) and silicon oxide (SiO ₂ ), these components do not affect the desulfurization and denitration catalyst activity.

[0034]

[Example 1] NOx / desulfurization performance was evaluated by using a fixed bed of manganese ore using various manganese ores having different manganese dioxide and aluminum oxide contents.
200 ppm, SOx: 200 ppm, O ₂ : 15%,
H ₂ O: 10%, using a simulated exhaust gas adjusted to the remaining N ₂ component, space velocity: 5000 hr ⁻¹ , reaction temperature: 120
It was performed under the condition of ° C.

FIG. 3 shows the relationship between the denitration rate, the manganese dioxide content rate, and the aluminum oxide content rate, and FIG. 4 shows the relationship between the desulfurization rate, the manganese dioxide content rate, and the aluminum oxide content rate. All are data 4 hours after the start of processing. When the manganese dioxide content is about 20%, both the denitration rate and the desulfurization rate tend to improve as the aluminum oxide content increases, but this is not remarkable. On the other hand, when the manganese dioxide content is 30% or more, the aluminum oxide content is about 5%, and the denitration rate and the desulfurization rate are significantly improved.

[0036]

Example 2 Manganese ores having different bound water contents were preheated in air at a temperature from room temperature to 700 ° C. for 1 hour, and then the denitration / desulfurization performance was evaluated using a fixed bed of the heat-treated manganese ores. NOx: 200ppm, SOx: 2
00ppm, O ₂ : 15%, H ₂ O: 10%, balance N ₂
Velocity: 100 using simulated exhaust gas adjusted to
The reaction was carried out under the conditions of 00 hr ⁻¹ and reaction temperature: 120 ° C.

FIG. 5 shows the relationship between the denitration rate, the bound water content rate and the preheat treatment temperature, and FIG. 6 shows the relationship between the desulfurization rate, the bound water content rate and the preheat treatment temperature. All are data 4 hours after the start of processing. When the bound water content is about 3%, the denitrification rate and desulfurization rate are slightly improved even if the heat treatment temperature rises, and the denitrification and desulfurization performance is lower than the ore not preheated at 600 ° C or higher. did. On the other hand, when the bound water is 5% or more and 10% or less, the denitration rate and the desulfurization rate are significantly improved when the heat treatment temperature is 400 ° C. or more,
When the temperature was higher than 0 ° C, the denitration and desulfurization performance deteriorated, and at 700 ° C, the denitration and desulfurization performance deteriorated as compared with the ore which was not preheated.

[0038]

Example 3 Sintered exhaust gas was treated using the apparatus whose flow is shown in FIG.

The exhaust gas A'exhausted from the sintering machine 1 and removed by the electrostatic precipitator 2 contains 50 mg / Nm ³ of SO and SO.
It contained 150 ppm of x and 150 ppm of NOx. This process gas volume 1,000 Nm ³ / hr, manganese ore moving layer 3 of capacity 0.3 m ³ in the exhaust gas temperature 120 ° C.
Ammonia D is introduced into the exhaust gas by the reaction of formula (3)
The total amount of stoichiometric amount of 300ppm, which is necessary to completely immobilize the sulfur oxides, and the stoichiometric amount of 150ppm used as a reducing agent in the reaction of formula (4), are adjusted to 450ppm in total. , Was added. The supply / discharge speed of manganese ore in the manganese ore moving layer 3 is 36 kg / hr.
Adjusted to. The manganese ore B ′ to which ammonium sulfate adhered was dissolved in water with a water washing facility 5 to remove the dust and ammonium sulfate water E, and the washed manganese ore B ″ was circulated and reused in the manganese ore moving layer 3.

Exhaust gas A ″ at the outlet of the manganese ore moving bed 3
When the manganese ore is new, the SOx concentration in A ″ is less than 1 ppm (detection limit 1 ppm, desulfurization rate: 99% or more), and the NOx concentration is less than 1 ppm (detection limit 1 ppm, denitration rate: 99%). It was). When the washing and recycling cycle was repeated, the desulfurization rate was maintained at 99% or more, but the denitration rate decreased and finally became stable at 50%.

The manganese ore used in the manganese ore moving layer 3 had a manganese dioxide content of 60 wt% and an aluminum oxide content of 10 wt%.

[0042]

Example 4 Sintered exhaust gas was treated using the apparatus whose flow is shown in FIG. Here Manganese ore volume of mobile phase 3 and 4 respectively 0.3m ^3, 0.3m ^3, respectively ore moving speed of 30kg / hr, and 6 kg / hr, total volume and ore moving speed of the moving layer 3 and 4 Is equal to the volume of the single moving bed 3 of Example 3 and the ore moving speed.

The exhaust gas A'exhausted from the sintering machine 1 and removed by the electrostatic precipitator 2 contains 50 mg / Nm ³ of SO and SO.
It contained 150 ppm of x and 150 ppm of NOx. This is introduced into the manganese ore moving bed 3 at a treatment gas amount of 1,000 Nm ³ / hr and an exhaust gas temperature of 120 ° C., and ammonia D is completely fixed by the reaction of the formula (3) in the exhaust gas A ′. 300ppm of stoichiometry necessary for
And the stoichiometric amount of 150 ppm used as a reducing agent in the reaction of the formula (4) were adjusted to be 450 ppm in total and added. The manganese ore B and the ammonia D were brought into contact with each other in the manganese ore moving layer 3 to perform advanced desulfurization of the exhaust gas and denitration with a denitration rate of 20%. Here, the supply / discharge rate of the manganese ore B was adjusted to 30 kg / hr, which is a rate at which 99% or more of sulfur oxides can be removed in the manganese ore moving layer 3. Manganese ore B'with ammonium sulfate attached
The ammonium sulfate was dissolved in water by a washing facility 5 to remove dust and ammonium sulfate water E, and the washed manganese ore B ″ was circulated and reused in the manganese ore moving layer 3.

Exhaust gas A ″ from which sulfur oxides were removed was introduced into the manganese ore moving layer 4 and ammonia catalytic reduction denitration was performed with ammonia not consumed in the manganese ore moving layer 3. The manganese ore C'extracted from the manganese ore moving layer 4 separated the dust F by the sieve 6, and the manganese ore C '' from which the dust was separated was circulated and reused in the manganese ore moving layer 4.

Analysis of the exhaust gas A ′ ″ at the outlet of the manganese ore moving bed 4 revealed that SOx was less than 1 ppm (detection limit 1 ppm, desulfurization rate: 99% or more), NOx was 1 pp.
It was less than m (detection limit 1 ppm, denitration rate: 99%). The desulfurization rate and denitration rate are 9 even after repeated washing and recycling.
9% or more could be maintained.

The manganese ore used in the manganese ore moving layers 3 and 4 has a manganese dioxide content of 60 wt% and an aluminum oxide content of 10 wt%. The substance and nitrogen oxide concentrations are values when the manganese ore is circulated and reused in each layer and the performance becomes stable.

[0047]

[Comparative Example 1] With the same apparatus and the same exhaust gas conditions as in Example 3,
The manganese ore B ′ discharged from the moving bed was separated from the surface-adhered ammonium sulfate and dust by sieving without washing with water and reused by circulation. Both desulfurization and denitration performance declined as a result of repeated circulation and reuse, and finally, no performance was exhibited.

[0048]

[Comparative Example 2] Desulfurization was carried out by absorption of sulfur oxides by manganese dioxide without adding ammonia to the manganese ore moving layer 3 under the same equipment and the same exhaust gas conditions as in Example 4, and the manganese ore moving layer 4 was contacted with ammonia. The treatment was performed by adding only the ammonia necessary for the reduction denitration. In the manganese ore moving layer 3, when the manganese ore is new, in order to remove the sulfur oxides to the same extent as in Example 4 by manganese sulfate in the manganese ore, the supply of manganese ore in the manganese ore moving layer 3 is performed. -It was necessary to set the discharge rate to 60 kg / hr, which is twice the speed in Example 4. Furthermore, although the oxidation catalyst function can be restored by dissolving and removing manganese sulfate in water by washing with water in the same manner as in Examples 3 and 4, when the washing and recycling cycle is repeated, the manganese dioxide content in the manganese ore decreases due to exhaustion of manganese dioxide. Therefore, the desulfurization performance was deteriorated, and the sulfur oxide-containing exhaust gas was introduced into the manganese ore moving bed 4, so that the denitration performance was also deteriorated.

When the exhaust gas A ′ ″ at the outlet of the manganese ore moving bed 4 was analyzed, it was finally found that SOx, NOx
Both the concentrations became the same as those in the exhaust gas A ', and the desulfurization / denitration performance was not exhibited.

[0050]

INDUSTRIAL APPLICABILITY The present invention enables efficient desulfurization and denitration at an exhaust gas temperature at low cost by utilizing manganese ore. Further, when the present invention is applied to flue gas denitration of a steel mill, used ore can be reused as a manganese source for iron making.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a flow of a method of the present invention.

FIG. 2 is a diagram showing another example of the flow of the method of the present invention.

FIG. 3 is a diagram showing a relationship among a denitration rate, a manganese dioxide content rate, and an aluminum oxide content rate.

FIG. 4 is a diagram showing a relationship among a desulfurization rate, a manganese dioxide content rate, and an aluminum oxide content rate.

FIG. 5 is a diagram showing a relationship among a denitration rate, a bound water content rate, and a preheating treatment temperature.

FIG. 6 is a diagram showing a relationship among a desulfurization rate, a bound water content rate, and a preheat treatment temperature.

[Explanation of symbols]

 1 Sintering machine 2 Electrostatic precipitator 3 Manganese ore moving bed 4 Manganese ore moving bed 5 Washing facility 6 Sieve A Exhaust gas A'Exhaust gas A '' Exhaust gas A '' 'Exhaust gas B Manganese ore B'Manganese ore B' 'Manganese ore C Manganese Ore C'Manganese ore C '' Manganese ore D Ammonia E dust, Ammonium sulfate F dust

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location B01J 23/92 ZAB A 38/48 A (72) Inventor Yasuyuki Izumi 20-1 Shintomi, Futtsu City, Chiba Prefecture Nippon Steel Corporation Corporate Technology Development Division

Claims (7)

[Claims] 1. Manganese dioxide 30 wt% or more and 80 w
t% or less, aluminum oxide 5 wt% or more 15 wt%
A desulfurization / denitration catalyst comprising the following manganese ore. 2. The desulfurization according to claim 1, which is composed of a manganese ore containing 5 wt% or more and 10 wt% or less of bound water and heat-treated at 400 ° C. or more and 600 ° C. or less.
DeNOx catalyst. 3. When removing nitrogen oxides in exhaust gas containing sulfur dioxide, sulfur dioxide in sulfur oxides in the exhaust gas is oxidized to sulfur trioxide using manganese ore as a catalyst,
A low-temperature exhaust gas dry denitration method containing sulfur oxides, which comprises removing sulfur oxides as ammonium sulfate with ammonia and simultaneously reducing and removing nitrogen oxides in exhaust gas by using manganese ore as a catalyst and ammonia as a reducing agent. 4. When removing nitrogen oxides in exhaust gas containing sulfur dioxide, sulfur dioxide in sulfur oxides in the exhaust gas is oxidized to sulfur trioxide using manganese ore as a catalyst,
A low-temperature exhaust gas dry denitration method containing sulfur oxides, characterized in that after removing sulfur oxides as ammonium sulfate with ammonia, manganese ore is used as a catalyst and nitrogen oxides in exhaust gas are reduced and removed using ammonia as a reducing agent. 5. When removing nitrogen oxides in the exhaust gas containing sulfur dioxide, the nitrogen oxide is connected in series to the flow of the exhaust gas.
Two manganese ore reactors are installed, of which the first reactor uses manganese ore as a catalyst to oxidize sulfur dioxide in sulfur oxides in exhaust gas to sulfur trioxide, and removes sulfur oxides as ammonium sulfate with ammonia. After that, a low-temperature exhaust gas dry denitration method containing sulfur oxides, characterized in that, in the second reactor, manganese ore is used as a catalyst and ammonia is used as a reducing agent to reduce and remove nitrogen oxides in the exhaust gas. 6. The sulfur oxide-containing low temperature exhaust gas dry denitration method according to any one of claims 3 to 5, wherein the manganese ore used for sulfur oxide removal is washed with water to remove ammonium sulfate attached to the manganese ore, A low-temperature exhaust gas dry denitration method containing sulfur oxides, characterized in that manganese ore is circulated and reused to remove sulfur oxides. 7. The method for removing sulfur oxides and nitrogen oxides in exhaust gas by using the desulfurization / denitration catalyst according to claim 1 or 2. Method for low temperature exhaust gas dry denitration containing sulfur oxides.