JP2003071241A - Acidic gas absorbing material, method for manufacturing the same and gas treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an acidic gas absorbing material having high strength and capable of utilizing the greater part of an acidic gas absorbing substance such as slaked lime, or the like, in the absorption of acidic gas, a method for manufacturing the acidic gas absorbing material and a gas treatment method using the acidic gas absorbing material. SOLUTION: The acidic gas absorbing material comprises core particles made of ceramic and an acidic gas absorbing layer covering the surfaces of the core particles. After the surface of the acidic gas absorbing material after the contact with acidic gas is ground, the acidic gas absorbing material is again used in the contact with the acidic gas.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an acidic gas absorbent,
The present invention relates to a manufacturing method thereof and a gas treatment method using the acidic gas absorbing material.

[0002]

2. Description of the Related Art Treatment methods for removing acidic gases such as hydrogen chloride, sulfur oxides, chlorine, etc. in exhaust gas generated from incinerators for industrial waste, municipal waste, sludge, etc. are wet method and dry method. Is roughly divided into

In the wet method, the harmful gas is contacted with an aqueous alkali solution or an alkaline slurry in a gas-liquid contactor such as a packed tower, a spray tower or a plate tower to absorb and remove the harmful gas.
Although this wet method has an advantage of high efficiency of removing harmful components, waste water containing ions such as sulfite ions, sulfate ions, and chlorine ions and harmful components of heavy metals is generated, and a high degree of wastewater treatment is required. Furthermore, when the processing gas is at a high temperature, the temperature of the exhaust gas is around 80 ° C and a large amount of water vapor is included, so white smoke is emitted when released into the atmosphere, and diffusion is insufficient, so white smoke is prevented by reheating, etc. There were drawbacks such as the need for equipment.

On the other hand, in the dry method, alkaline powder or particles such as calcium hydroxide or calcium carbonate is used as an absorbent material, and exhaust gas is absorbed through an exhaust gas through a packed bed of the absorbent material, or absorbent powder is provided in an exhaust gas passage. It is a method of spraying and reacting with acidic gas, and then collecting.

Since this dry method is based on the direct contact reaction between the high temperature gas and the solid absorbent, no waste water is generated and no white smoke is generated.

Among the dry methods, as a gas treatment method of passing exhaust gas through a layer filled with an absorbent, an acidic gas obtained by pelletizing an alkaline substance such as massive calcium oxide, calcium carbonate, or calcium hydroxide into pellets Forming a packed bed of the absorbent, continuously or intermittently withdrawing the acidic gas absorbent that has absorbed the acidic gas from the lower part of the packed bed, continuously or intermittently supplying the acidic gas absorbent from above,
There is a method in which the acidic gas absorbent is brought into contact with the gas while moving in the packed bed. In this method, the surface of the acidic gas absorbent taken out from the packed bed is covered with the reaction product, and unreacted alkali remains inside the particles, so the reaction product was separated from the surface and separated. After that, it is returned to the upper part of the packed bed for reuse.

[0007]

The above-mentioned conventional acidic gas absorbent comprising a granulated body of calcium oxide has a low crushing strength and is easily pulverized to increase the ventilation pressure loss. Further, when the reaction product is peeled from the surface and reused, the particle size becomes smaller each time it is reused. If the particle size becomes small, the ventilation pressure loss of the packed bed will increase, and gas treatment will be hindered.If the particle size becomes small to some extent, the acidic gas absorbent will be discarded despite the unreacted alkaline substance remaining. There is much waste of alkaline substances. In addition, since the waste is alkaline, it requires neutralization before disposal.
New processing costs arise.

The present invention solves these problems, has a high crushing strength, and is an acidic gas absorbing substance (alkali substance).
It is an object of the present invention to provide an acidic gas absorbent capable of utilizing all or most of the above for absorbing acidic gas, a method for producing the same, and a gas treatment method using the acidic gas absorbent.

[0009]

The acidic gas absorbing material of the present invention comprises ceramic core particles and an acid gas absorbing layer covering the surfaces of the core particles.

This acidic gas absorbing material is produced by depositing an acidic gas absorbing substance on the surface of ceramic core particles.

The gas treatment method of the present invention is a method of contacting the core particles of the present invention with a gas to absorb an acidic gas,
After polishing the surface of the acidic gas absorbent after contact with the acidic gas, the acidic gas absorbent is used again for contact with the gas.

Since the core particles of the acidic gas absorbent of the present invention are made of ceramic, they are not cracked or crushed and have high particle strength.

When the acidic gas absorbing material comes into contact with the acidic gas, the acidic gas absorbing reaction gradually progresses from the surface, and the acidic gas absorbing rate decreases. Therefore, when this surface is polished to remove the reaction product, the acid gas absorption rate of the acid gas absorbent is restored.

This acid gas absorbing material is discarded as all or most of the acid gas absorbing material layer is eventually lost after repeated polishing. Therefore, all or most of the acidic gas absorbing substance can be used for absorbing the acidic gas.

The particles used up were only the ceramic core particles and some acidic gas absorbing substances, and almost all of the acidic gas absorbing substances remaining at the end reacted with the acidic gas to be neutralized. Therefore, it can be disposed of without the need for a separate neutralization treatment. Further, the core particles may be reused for the production of a new acid gas absorbent.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION As the ceramic constituting the core particles of the acidic gas absorbent of the present invention, crushed products of ceramic products are suitable, for example, crushed products and tiles of various ceramic products such as tiles and sanitary ware. Those obtained by sieving the crushed product of 1. The particle size of the core particles is 1 to 6 mm, especially 2 to
About 5 mm is suitable. The core particles preferably have a water absorption rate of about 5 to 30% (24-hour water absorption rate).
If the water absorption is too high, the strength of the core particles is low, while if the water absorption is too low, it becomes difficult to attach the acidic gas absorption layer to the surface of the core particles.

As the acidic gas absorbing substance deposited on the surface of the core particles, calcium-based alkaline substances such as quick lime, slaked lime and calcium carbonate are preferable, but quick lime or slaked lime is preferable because of its high absorption capacity. The acidic gas absorbing substance may be composed of only an alkaline substance, and may contain a small amount (for example, about 10% by weight or less) of a plasticizer component such as clay in order to enhance the strength of the adhesion coating layer.

To attach the acidic gas absorbing substance to the surface of the core particles, water is absorbed by the core particles, and then the powder is mixed with powder of the acidic gas absorbing substance, and the powder is sprinkled on the core particles. It is preferably applied and then dried. At the time of this mixing, it is preferable to finish the acidic gas absorbing material into a spherical shape using a rotary mixer, a rolling granulator or the like.

In the case of slaked lime or calcium carbonate, the slurry may be mixed with the core particles to be adhered to the surface of the core particles, and the core particles may be dried while rolling to form a coating layer on the surface of the core particles. .

The particle size of the acidic gas absorbing material thus obtained by forming the acidic gas absorbing substance layer on the surface of the core particles is 4 to 10
About mm is preferable.

In order to bring the acid gas absorbent thus produced and the gas to be treated into contact with each other, a packed layer of the acid gas absorbent is formed, and the gas to be treated is aerated through the packed layer. It is preferable that the acidic gas absorbent is taken out from a part of the above, polished, and then returned to the packed bed again. In particular, the gas to be treated is ventilated from the lower part of the packed bed in an upward flow, the acidic gas absorbent is continuously taken out little by little from the lower part of the packed layer, and the polishing treatment is performed. It is preferred to replace the absorbent material. In this case, it is preferable that the acid gas absorbent that has been subjected to the polishing treatment is sieved to discard the particles having a predetermined particle size or less, and a new feed of the acid gas absorbent is supplied in an amount commensurate with the discarded amount.

[0022]

EXAMPLES Examples will be described below.

(1) Production of Acid Gas Absorbing Material Defective roof tiles were crushed and sieved to a particle size of 3 to 6 mm to obtain core particles. After 50 parts by weight of water was absorbed in 100 parts by weight of the core particles, the mixture was put into a paddle type mixer together with 300 parts by weight of commercially available powdered slaked lime, and the mixture was stirred at a low speed for 5 minutes. Separated into granules (acidic gas absorbent). The average particle size of the granulated product was 8 mm.

(2) Acid Gas Absorption Experiment 100 g of the acid gas absorbent obtained by the above (1) was used for the inner diameter 5
It was filled in a 0 mm U-shaped glass tube. 2.5 L / mi of air having a hydrogen chloride gas concentration of 1000 ppm was put into this glass tube.
Aeration was performed at a rate of n. The hydrogen chloride gas concentration in the outflow gas at the beginning of aeration was 4 ppm.

Since the hydrogen chloride gas concentration in the outflow gas had risen to 100 ppm after 200 hours had passed, ventilation was stopped, the acidic gas absorbent was taken out, and the surface was polished with a vibrating sieve. The average particle size of the acid gas absorbent after polishing was 8 mm.

When the acidic gas absorbing material was filled in the glass tube again and a hydrogen chloride gas-containing gas was aerated under the same conditions, the hydrogen chloride gas concentration in the outflow gas was 4 ppm.

At the time when 180 hours passed, the hydrogen chloride gas concentration in the outflow gas had risen to 100 ppm, so ventilation was stopped and polishing was carried out again. The average particle size of the acid gas absorbent after polishing was 6 mm.

When the acidic gas absorbing material was filled in the glass tube again and aerated under the same conditions, the hydrogen chloride gas concentration in the outflow gas was 4 ppm. Since the hydrogen chloride gas concentration in the outflow gas had risen to 100 ppm after the lapse of 150 hours, ventilation was stopped and the acidic gas absorbent was taken out. When the surface layer was peeled from this acidic gas absorbent and analyzed, it was found that CaCl ₂ and Ca (OH) ₂
The ratio of Ca (OH) _{2 to} the total of the above was 20 mol%.

[0029]

As is apparent from the above examples, according to the present invention, an acidic gas absorbent having high strength and capable of utilizing most of the acidic gas absorbent such as slaked lime for absorbing acidic gas. And a method of manufacturing this acidic gas absorbent,
A gas treatment method using the acidic gas absorbent is provided.

Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B01J 20/04 B01D 53/34 124Z 20/32 ZAB 20/34 F term (reference) 4D002 AA02 AA18 AA19 AB01 AC04 BA03 CA07 CA08 DA05 DA12 DA16 EA07 EA13 4G004 BA00 4G066 AA17B AA72C CA23 CA31 DA02 FA01 FA11 GA40

Claims (5)

[Claims] 1. An acidic gas absorbing material comprising ceramic core particles and an acid gas absorbing layer covering the surfaces of the core particles. 2. The acid gas absorbent according to claim 1, wherein the core particles are crushed products of ceramic products. 3. The method for producing an acidic gas absorbent according to claim 1, wherein the acidic gas absorbent is attached to the surface of ceramic core particles. Production method. 4. The acidic gas according to claim 3, wherein after the water is absorbed by the core particles, the core particles are mixed with the powder of the base material for absorbing the acid gas to adhere the base material to the surface of the core particles. Absorbent manufacturing method. 5. A gas treatment method in which an acidic gas absorbent and an object gas containing the acidic gas are brought into contact with each other to allow the acidic gas absorbent to absorb the acidic gas, wherein the acidic gas absorbent is the method according to claim 1 or 2. The acid gas absorbing material is characterized in that after polishing the surface of the acid gas absorbing material after contact with the acid gas, the acid gas absorbing material is brought into contact with the gas to be treated again.