JPH05220343A - Method for removing gaseous hydrogen chloride discharge from incineration plant of waste - Google Patents

Abstract

PURPOSE:To easily solve such trouble that environment is deteriorated with incineration by efficiently removing gaseous hydrogen chloride discharged from incinerating treatment of waste and also decreasing the concentration of soot and dust. CONSTITUTION:Porous granules consisting of calcium silicate are obtained as follows and used. Aluminum powder is added to slurry containing 65wt.% siliceous raw material and 35wt.% calcareous raw material as a main raw material. The mixture is foamed, cured and treated by hydro-thermal reaction. Obtained CSH gel and tobermorite are ground and the grain size is regulated. In incinerating treatment, gaseous hydrogen chloride generated from an incinerator 1 is introduced into a flue 2 and thereafter the granules are supplied at 16kg/hr from a spout 6 and brought into contact with gaseous hydrogen chloride and recovered by an electrostatic precipitator 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for incinerating waste.

[0002]

2. Description of the Related Art Conventionally, when incinerating waste, emission standards for harmful substances have been established based on the Air Pollution Control Act, and hydrogen chloride gas that is generally emitted from waste incinerators is removed and collected. It is being appreciated. As the method, slaked lime, quick lime, calcium carbonate or the like as a neutralizing agent is made into a powder form or a slurry form, and the gas is adsorbed by contacting with hydrogen chloride gas in the exhaust gas generated by waste incineration, It is collected by an electric dust collector. Regarding the treatment of the mixture of the neutralizing agent and the fly ash, there is a method of recovering the mixture in an ash pit, a cooling water tank or the like, performing precipitation or dehydration separation, and then performing landfill treatment. Further, as another method, there is a wet method in which hydrogen chloride gas is absorbed in an alkaline aqueous solution such as caustic soda for neutralization.

[0003]

However, in the above-mentioned treatment, the concentration of hydrogen chloride gas discharged from the waste incineration plant may become high depending on the waste or the like. Hydrogen chloride gas cannot be sufficiently removed only by neutralizing with an amount of a disinfectant, and the emission standard value is exceeded due to a decrease in the removal rate. Therefore, if a large amount of a neutralizing agent is used, high cost and recovery efficiency by an electrostatic precipitator, etc. There was a problem that In addition, when quick lime is used in the above method, quick lime is a water-prohibiting substance, and therefore care must be taken when handling it. Furthermore, when ash is transferred by a screw conveyor etc. in fly ash recovery, scale is generated due to calcium leached in the equipment and constant cleaning is required, or wet recovery of wet ash cooling device, cooling water tank, etc. When the device is used, it is necessary to perform wastewater treatment of ash wastewater, and at that time, there is a problem that scale is generated in the water supply pipe of the ash wastewater due to the eluted calcium and clogging occurs.

In the wet method using an alkaline aqueous solution, the installation of the neutralization tank wastewater treatment equipment makes the equipment complicated and expensive, and it is necessary to manage the wastewater. In view of the above points, it is an object of the present invention to provide a method for efficiently removing hydrogen chloride gas generated during waste incineration by a simple method.

[0005]

DISCLOSURE OF THE INVENTION The present invention is characterized in that hydrogen chloride gas generated during waste incineration is removed by bringing it into contact with a porous powdery or granular material composed of calcium silicate hydrate. It is a method of incinerating things. Examples of the porous powdery particles made of calcium silicate hydrate used in the present invention include siliceous raw materials such as silica and lime,
A slurry-like product obtained by mixing a calcareous raw material such as cement into a slurry form as it is at high temperature and high-pressure steam, or a slurry-like product obtained by mixing the slurry with a foaming agent such as a foaming agent or a foaming agent. Examples thereof include inorganic porous artificial minerals obtained by curing in a high temperature and high pressure steam after being hardened.

Specific components of the calcium silicate hydrate of the porous powdery or granular material of the present invention include tobermorite, xonotlite, CSH gel, and the like containing one or more calcium silicate hydrates as main components. be able to. The particle size of the above-mentioned porous powdery particles of calcium silicate hydrate is not particularly limited, but the particle size is 2 mm or less and the specific surface area is 5 m ² /
It is preferably g (BET method) or more.

The amount of the porous powdery particles made of the calcium silicate hydrate to be used may be appropriately adjusted so as to be equal to or less than the emission standard value of hydrogen chloride gas. Generally, in waste incineration, hydrogen chloride gas generated from an incinerator is discharged to the outside from the incinerator through a flue. In the present invention, the contact between the porous powdery particles made of the calcium silicate hydrate and the generated hydrogen chloride gas is at any point during the process as long as it is before a fly ash recovery facility such as an electrostatic precipitator. Although it is good, specifically, it may be mixed in an incinerator, a flue, or pre-incineration waste in advance. Further, they may be combined and used at one place or two places.

According to the method of the present invention, soot and dust can be largely removed and recovered at the same time as hydrogen chloride generated by incineration. Furthermore, if it is mixed in advance with the waste before incineration, the effect of removing the bad odor of the waste can be expected.

[0009]

With the above structure, the efficiency of removing hydrogen chloride gas is improved as compared with the prior art. This is due to the following action. Since it is a porous body, it has a large surface area and a large contact area with hydrogen chloride gas and dust. Since it is a porous body, it has a high water content and retains water even though it is an apparent powder. Therefore, hydrogen chloride gas having a high solubility in water can be effectively absorbed and removed. Since calcium silicate hydrate is alkaline, it can be neutralized with hydrogen chloride gas. Has a lower solubility of calcium in water than calcareous substances. Therefore, problems such as solidification and blockage in fly ash treatment equipment and ash sewage treatment equipment do not occur. Since it is made of an inorganic stable substance and has heat resistance, there are no restrictions on where it is used. Since it is a porous lightweight powder, it is easy to carry out spraying and the like in air transportation, dry method and the like.

[0010]

EXAMPLES The present invention will be specifically described below based on examples.

[0011]

[Example 1 and Comparative Examples 1 and 2] The porous powdery granules made of calcium silicate hydrate used for removing hydrogen chloride gas contain 65 wt% of siliceous raw material and 35 wt% of calcareous raw material as main raw materials. After adding aluminum powder to the slurry to foam and cure it, CSH gel and tobermorite obtained by hydrothermal reaction treatment under high temperature and high pressure were crushed by a crusher, and the particle size was adjusted. The particle size was 2 mm or less, and the specific surface area was 40 m ² / g (BET method).

An incineration test was conducted using about 17 tons of combustible waste collected in N town, Shizuoka prefecture, using the above-mentioned porous powdery particles of calcium silicate hydrate as a hydrogen chloride removing agent. FIG. 1 is a schematic diagram of an incineration treatment facility. In FIG. 1, 1 is an incinerator, 2 is a flue, 3 is a cooling device, 4 is an electrostatic precipitator, 5
Is a chimney, 6 is a porous powdery particle jet outlet, and 7 is a sample collection port.

Combustible waste is incinerated at about 850 ° C. in an incinerator 1, and a gas containing hydrogen chloride gas generated from the incinerator 1 passes through a flue 2 and is then cooled in order to secure the capacity of an electric dust collector 4 for collecting dust. The gas is cooled by the device 3 and discharged from the chimney 5 via the electrostatic precipitator 4. The porous powdery particles made of calcium silicate hydrate are porous powdery particles ejection ports 6 to 16
Supplied in Kg / hr. A gas containing hydrogen chloride gas discharged at that time was sampled from the sample collection port 7 at a constant flow rate to measure the hydrogen chloride gas concentration. Moreover, the amount of dust was measured by the cylindrical filtration method. The results are shown in Table 1.
Shown in.

As Comparative Example 1, incineration treatment was carried out in the same manner as in Example 1 except that slaked lime was supplied from the porous powdery or granular material jet port 6 in FIG. 1 at a rate of 16 kg / hr. The incineration process was performed in the same manner as in the example except that the porous powdery particles were not added, and the concentration of hydrogen chloride gas in the discharged gas and the amount of dust were measured. The results are shown in Table 1.

As shown in Table 1, the hydrogen chloride concentration in the exhaust gas of Example 1 was lower than that of Comparative Examples 1 and 2. The above facts indicate that the porous granular material made of calcium silicate has an excellent ability to recover hydrogen chloride generated by incineration. When the ash collected in Example 1 was subjected to the elution test stipulated in the Environmental Agency Notification No. 13, the leaching amount of each of the stipulated substances was below the lower limit of quantification, and the standard detection value was significantly increased. It was below the result.

[0016]

[Table 1]

[0017]

Example 2 and Comparative Example 3 Each powder used in Example 1 and Comparative Example 1 was dipped in water at 5% by weight, and as Example 2 and Comparative Example 3, the elution amount of calcium was ED.
Determined by TA titration method. The results are shown in Table 2.
As shown in Table 2, the elution amount of calcium in Example 2 was smaller than that in Comparative Example 3. The above facts indicate that the calcium elution amount, which is a factor of blockage due to scale, is reduced, and the solidification of the ash transfer equipment such as the screw conveyor to the screw and the like, the clogging of the wastewater system equipment, and the solidification are eliminated. Indicates.

[0018]

[Table 2]

[0019]

With the structure of the present invention, hydrogen chloride gas generated during incineration can be efficiently removed, and the amount of dust and soot can be reduced to prevent deterioration of the environment associated with incineration. Further, since the porous body made of calcium silicate hydrate used in the method of the present invention is made of an inorganic substance, it does not have a water-prohibiting property such as the generation of harmful substances due to decomposition and quicklime, and also retains water in the pores. Therefore, it can effectively absorb easily water-soluble hydrogen gas, and at the time of incineration, regardless of the quality and quantity of waste, it is easy to install neutralization tank wastewater treatment equipment and manage wastewater. It has an excellent effect that it can be processed. In addition, when the fly ash is collected or transferred in the cooling water tank, the scale or the like generated from the fly ash does not cause clogging or solidification.

Further, if a porous body made of calcium silicate hydrate is premixed with the waste before incineration, a bad odor removing effect of the waste can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an incineration treatment facility according to an embodiment of the present invention.

[Explanation of symbols]

 1. Incinerator 2. Flue 3. Cooling device 4. Electric dust collector 5. Chimney 6. Porous powder ejection port 7. Sample collection port 8. Waste 9. Exhaust gas

Claims (1)

[Claims] 1. A method for incineration of waste, which comprises removing hydrogen chloride gas generated during incineration of waste by contacting it with a porous granular material made of calcium silicate hydrate.