JPH11555A - Desulfurizing and denitrating agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a desulfurizing and denitrating agent capable of enhancing denitrating performance while maintaining strength and desulfurizing performance by preparing a desulfurizing and denitrating agent suitable for the desulfurization and denitration of waste gas from a thermoelectric power plant using coal, a sintering furnace, etc., from a material having a specified amt. of org. oxygen. SOLUTION: The desulfurizing and denitrating agent is prepd. from a material having 3-15 wt.% org. oxygen obtd. using stock selected from among various carbon materials and oxides such as V2 O5 , Fe2 O3 , CuO, MoO3 and WO3 /TiO2 carrier, preferably activated carbon made from coconut husks, activated carbon made from coal, chemically activated carbon and activated coke as carbon materials having >=1 μm particle diameter. Activated coke is especially preferably used from the viewpoint of strength, gas permeation resistance and cost. Gas used for oxidation treatment is preferably air, a nitrogen-oxygen mixture or a CO2 -oxygen mixture and the concn. of oxygen in the gas is preferably regulated to 10-21% so as to prevent the reduction of strength and to effectively exhibit denitrating performance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a desulfurization and denitration agent, and more particularly to a desulfurization and denitration agent suitable for desulfurization and denitration of exhaust gas from coal-fired power plants and sintering furnaces.

[0002]

SO _x and NO BACKGROUND ART In exhaust gas generated from thermal power plants burning coal or heavy oil, or various sintering furnace
The removal of _x is important in protecting the global environment, and its technology is also diverse. However, carbon materials called activated coke are mainly used for dry desulfurization and denitration.

The following methods are known as desulfurization and denitration treatment using a carbon material. After wet desulfurization, dry denitration is performed. A two-stage treatment system in which desulfurization is performed in a dry process and then denitration is performed in a dry process. Simultaneous desulfurization and denitration method for simultaneous desulfurization and denitration. The desulfurization performance of the carbon materials used in these methods is S-BE
It is known that the specific surface area can be improved by increasing the specific surface area measured by the T method (multipoint method). However, with respect to denitration, satisfactory results have not been obtained with conventional carbon materials.

[0004] As a countermeasure, a method of using a metal oxide such as titanium oxide as a denitration catalyst, a method of drying a carbon material after sulfuric acid treatment and increasing a denitration capability (Japanese Patent Publication No. 2-482)
See No. 94 publication. ), But there is no satisfactory method in terms of performance and cost.

[0005]

SUMMARY OF THE INVENTION The present inventors have conducted extensive research to develop a carbon material or the like having sufficient desulfurization and denitrification capabilities at a low cost, and as a result, the oxygen contained in the carbon material and the like is It is classified into organic oxygen contained in the carbon structure and inorganic oxygen contained as metal oxides in the ash, but we know that there is a correlation between the amount of organic oxygen and the denitration ability. In addition, further research was conducted to increase the amount of organic oxygen in the carbon material by adding organic oxygen to the carbon material such as activated carbon and activated coke by gas phase oxidation, etc., to maintain the strength and desulfurization performance and improve the denitration performance. The present invention has been reached, knowing that it can be improved. The amount of organic oxygen in the present invention is a value obtained by subtracting the amount of inorganic oxygen from the total amount of oxygen contained in the carbon material or the like and dividing the result by the weight of the carbon material, expressed as a percentage.

[0006]

SUMMARY OF THE INVENTION The present invention provides a desulfurizing and denitrifying agent comprising a material having an organic oxygen content in the range of 3 to 15% by weight, preferably a carbon material.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The organic oxygen content of the present invention is from 3% by weight to
In preparing a material having desulfurization and denitration performance in the range of 15% by weight, the raw material used is not particularly limited, but various carbon materials, V ₂ O ₅ , Fe ₂ O ₃ , CuO,
It is general to select from oxides such as MoO ₃ and WO ₃ / TiO ₂ carriers. Coconut shell activated carbon with a particle size (primary particle size) of 1 micron or more in terms of performance, manufacturing cost, etc.
Carbon materials such as coal-based activated carbon, chemical activated carbon and activated coke are preferred. Among them, activated coke is particularly preferred in view of strength, ventilation resistance, and price. Hereinafter, the case of a carbon material will be described. Even when the oxide-based material is used, desulfurization and denitration performance can be improved by setting the amount of organic oxygen to be in a range of 3% by weight to 15% by weight.

[0008] The oxidation treatment temperature is usually 300 to 60
0 ° C is chosen. When the treatment temperature is lower than 300 ° C., the effect of improving the denitration capability is small. When the temperature is 600 ° C. or higher, the loss of the carbon material due to combustion becomes large. Therefore, the range of 400 to 500 ° C. is desirable for preventing the reduction of the strength and the burning of the carbon material at the time of the oxidation treatment, and for the effective manifestation of the denitration performance.

As the gas used for the oxidation treatment, an oxygen-containing gas or SO ₂ , NO, or the like can be used. However, in consideration of the control of the degree of oxidation, the ease of handling the gas, and the cost, the air, nitrogen + Oxygen and CO ₂ + oxygen are good. The oxygen concentration in the gas is 5 to 30%, preferably 10 to 21% in order to prevent a decrease in strength and to effectively exhibit denitration performance.

In order to adjust the oxygen concentration and the temperature,
The same effect can be obtained by using exhaust gas from a combustion furnace or a mixture of the exhaust gas and steam. An ozone-containing gas can be used as the oxidizing gas. In this case, ozone is decomposed in the above temperature range. The ozone concentration is 1 to 10%, preferably 3 to 7% for the same reason.

As the method of the oxidation treatment, a kiln, a multi-stage furnace, a shaft furnace, a fluidized bed and the like can be used. As a method of inserting the gas for the oxidation treatment, the carbon material and the gas flow can be either countercurrent or cocurrent. The heating method can be either external heat or internal heat. In the practice of the present invention, when responding to the fluctuation of the raw material and changing the target value of the amount of organic oxygen, for example, the oxygen concentration on the gas inlet side and the outlet side was measured by an oxygen analyzer such as a magnetic type or a zirconia type. The amount of oxygen consumed for the oxidation reaction of the carbon material is calculated from the change in the oxygen concentration, and the carbon material having the target amount of organic oxygen can be obtained by adjusting the oxygen concentration or the oxidation temperature.

The organic oxygen content of the carbon material according to the present invention is 3 to 1
It is desirably 5% by weight, preferably 3.5 to 7% by weight. More preferably, it has a volatile content of 3.5% by weight or more. When the amount of organic oxygen is less than 3.5% by weight, the effect of improving the denitration performance is reduced, and when the amount of organic oxygen is 7% by weight or more, the denitration performance is remarkably improved, but the carbon material substrate becomes fragile and the strength is reduced. The powder is liable to wear due to powdering during handling, and powdering in the adsorption tower and the regeneration yield during regeneration are reduced. When the amount of organic oxygen is 15% or more, these become remarkable, so that they do not function as a carbon material for desulfurization and denitration.

[0013]

EXAMPLES Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof. The amount of organic oxygen, desulfurization performance, denitration performance, volatile content and strength were determined by the following measurement methods. [Amount of organic oxygen] As a device, a TC-436 oxygen-nitrogen simultaneous analyzer manufactured by LECO was used. This measurement method can be obtained by measuring the total oxygen content in the carbon material at a constant temperature, then measuring the inorganic oxygen content by two-stage extraction measurement, and calculating the organic oxygen content.

(1) Measurement of Total Oxygen Content by Extraction at Constant Temperature The sample is finely pulverized to 90% or more through a JIS sieve mesh of 325 mesh and dried at 115 ° C. for 1 hour. 10 mg of the dried sample is weighed and set in the device. For the extraction, a dedicated nickel capsule is used, and extraction is performed at an extraction temperature of 2300 ° C. for 150 seconds, and the total oxygen content is calculated as a percentage by weight based on the sample weight.

(2) Measurement by Two-Step Extraction The sample is finely pulverized to 90% or more through a JIS sieve mesh of 325 mesh, and dried at 115 ° C. for 1 hour. 10 mg of the dried sample is weighed and set in the device. For the extraction, a dedicated nickel capsule is used, and the first stage extraction is performed at 1150 ° C. for 200 seconds to extract and remove organic oxygen in the sample. After removing the organic oxygen, the second stage extraction is performed at 2300 ° C. for 200 seconds, and the remaining inorganic oxygen is extracted and quantified.

(3) Calculation of the amount of organic oxygen The amount of organic oxygen can be obtained by removing the amount of inorganic oxygen obtained by the two-stage extraction from the total amount of oxygen obtained by constant temperature extraction.

[0017]

(Equation 1)

[Strength] A sample on the sieve sieved at 1.2 mm is dried at 120 ° C. for 3 hours to obtain about 2000 g. 2. Insert the sample into the rotating drum tester, and
Rotate for time, sieve the sample through a 2.0 mm sieve,
A sample having a thickness of 2.0 mm or more is weighed after drying, and the result is shown in% by weight based on the initial sample weight. [Volatile content] The volatile component is analyzed according to JIS-M-8812 analysis method.

[Denitration performance] One liter of the sample is filled in a container having an inner diameter of 52.7 mm, and pretreated at 400 ° C. for 3 hours in a stream of N ₂ . 2. In a container filled with a sample, 300 ppm of NO, NH
₃ A mixed gas of 300 ppm, 7.8% of H ₂ O, 3.8% of O ₂ , and the remaining N ₂ is aerated at 800 Nl / hour at a reaction temperature of 145 ° C. 3. In this state, ventilation was continued for 24 hours, and the average denitration rate for 24 hours

[0020]

(Equation 2)

[Desulfurization performance] About 425 ml of sample is dried at 120 ° C. for 3 hours. 2. In a container filled with the sample, 1020 ppm of SO ₂ , O
₂ 6.4%, H ₂ O 9.8%, remaining N ₂ mixed gas of 26
Bubble at 120 ° C. for 5 hours at Nl / min to adsorb SO ₂ . 3. After adsorption, 400 ° C. in a stream of N ₂ at 5 L / min.
And kept for 3 hours to desorb. 4. 5. The desorbed gas is collected by a 2-connected absorption bottle containing 2 liters of 3% hydrogen peroxide solution, and JIS-K0103.
1 Analyze and calculate by the neutralization method.

Example 1 After blending 70% by weight of weakly caking coal and 30% by weight of caking coal,
50 parts of a load tar pulverized to 90% or more through a 00 mesh and heated to 150 ° C. were added and kneaded with a kneader equipped with an SM jacket for 15 minutes. This kneaded material is used for a diameter 11
10 mm with a press extruder equipped with a mmφ die
Granulated at a pressure of 0 to 130 kg / cm ² and a length of 10 to 1
5 mm pellets were obtained. The pellets are subjected to 85% by volume of nitrogen and 15% by volume of water vapor in an externally heated rotary kiln.
Was supplied at a rate of 4 ° C./min. The obtained carbide is subjected to 850
A mixed gas of 50% by volume of nitrogen and 50% by volume of steam was passed at 3 Nl / min at 1 ° C. for 1 hour, activated to obtain a mother body before the oxidation treatment. 300 g of the base was placed in an externally heated rotary kiln, and nitrogen + oxygen gas adjusted to an oxygen concentration of 16% was added to a rotary kiln.
Gas was passed at Nl / min, the internal temperature was raised to 450 ° C, and oxidation treatment was performed for 80 minutes. The obtained product was measured for desulfurization and denitration rate, strength, amount of organic oxygen, and volatile matter.
The result shown in FIG.

Example 2 Except that a commercially available activated coke for desulfurization and denitration was used as a base to be subjected to the oxidation treatment, a sample oxidized under the same conditions as in Example 1 was subjected to desulfurization and denitration rate, strength, amount of organic oxygen and volatile matter. The measurement was performed, and the results shown in Table 1 were obtained. Example 3 Measurement of desulfurization and denitration rate, strength, amount of organic oxygen, and volatile matter were carried out on the same oxidized sample as in Example 1 except that ozone was used for the oxidation treatment and the ozone concentration was 5% and the test was performed at 40 ° C. The results were as shown in Table 1.

Example 4 The blending of raw coal was carried out by using 40% by weight of weak caking coal and 25% by weight of caking coal.
It was manufactured under the same conditions as in Example 1 except that the weight was changed to 35% by weight. The desulfurization and denitration rate, strength, organic oxygen content, and volatile content of the obtained product were measured, and the results shown in Table 1 were obtained. Example 5 The same treatment as in Example 1 was performed except that the oxidation treatment was performed at 500 ° C. for 120 minutes at an oxygen concentration of 21%. The desulfurization and denitration rate, strength, organic oxygen content, and volatile content of the obtained product were measured, and the results shown in Table 1 were obtained.

Example 6 The same conditions as in Example 1 were used except that the oxidation treatment was performed at 400 ° C. for 60 minutes at an oxygen concentration of 16%. The desulfurization and denitration rate, strength, organic oxygen content, and volatile content of the obtained product were measured, and the results shown in Table 1 were obtained. Example 7 Measurement of desulfurization denitrification rate, strength, amount of organic oxygen, and volatile matter of a product obtained by oxidizing the commercially available activated coke for desulfurization and denitration of Example 2 at 550 ° C. for 120 minutes at an oxygen concentration of 21% Was carried out, and the results shown in Table 1 were obtained. Example 8 A product was obtained under the same conditions as in Example 1 except that "non-caking coal having a high volatile content" was used instead of "weakly caking coal". The desulfurization and denitration rate, strength, amount of organic oxygen, and volatile matter were measured.
Were obtained.

Comparative Example 1 A product was obtained under the same conditions as in Example 1 except that the oxidation treatment was not performed. The desulfurization and denitration rate, strength, organic oxygen content, and volatile content of the obtained product were measured, and the results shown in Table 1 were obtained. Comparative Example 2 A product was obtained under the same conditions as in Example 4 except that the oxidation treatment was not performed. The desulfurization and denitration rate, strength, organic oxygen content, and volatile content of the obtained product were measured, and the results shown in Table 1 were obtained. Comparative Example 3 Except that the oxidation treatment was not performed, the desulfurization and denitration rate, strength, organic oxygen content, and volatile content of the commercial product of Example 2 were measured, and the results shown in Table 1 were obtained.

[0027]

[Table 1]

[0028]

According to the present invention, it is possible to provide an inexpensive and excellent desulfurizing and denitrifying agent having an extremely high performance. In addition, its production method is based on various carbon materials including activated carbon and activated coke as well as commercially available carbon-based adsorbents. It is easy to produce a desulfurization and denitration agent with the performance of
In addition, it greatly contributes to maintaining a good environment.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mitsushi Matsumoto 1-1 Kurosaki Castle Stone, Yawatanishi-ku, Kitakyushu City Inside the Kurosaki Office of Mitsubishi Chemical Corporation (72) Inventor Koji Dobashi 2-5-2-2 Marunouchi, Chiyoda-ku, Tokyo 3 (72) Inventor Teruo Watanabe 2-1-1 Tanidocho, Tanashi-shi, Tokyo Sumitomo Heavy Industries, Ltd.

Claims (6)

[Claims] 1. A desulfurizing and denitrifying agent comprising a material having an organic oxygen content in a range of 3% by weight to 15% by weight. 2. The desulfurization and denitration agent according to claim 1, wherein the volatile matter is at least 3.5% by weight. 3. The desulfurization and denitration agent according to claim 1, wherein the particle size is 1 μm or more. 4. The desulfurization and denitration agent according to claim 1, wherein the material is a carbon material. 5. The desulfurization and denitration agent according to claim 4, which is obtained by oxidizing a raw carbon material. 6. The desulfurization and denitration agent according to claim 5, wherein the raw material carbon material is activated coke.