Waste incineration method and waste incineration apparatus

Abstract

To promote carbonation of incineration ash and immobilization of heavy metals in a waste incinerator.SOLUTION: In a waste incineration method for burning waste and discharging the waste as incineration ash, an incinerator includes a combustion chamber for burning waste, and the combustion chamber includes in a flowing direction of the waste: an initial combustion region for performing initial combustion after the waste is dried; a main combustion region for burning a solid content of the waste and generated combustible gas; a post-combustion region for burning unburned contents of the waste to convert the contents into incineration ash; and an ash carbonation region for applying carbonation treatment to the incineration ash. After least part of exhaust gas in the incinerator is branched as circulation exhaust gas by circulation exhaust gas supply means, gas containing oxygen as a main constituent is mixed with the circulation exhaust gas by oxygen supply means to generate mixed gas with 50% or more of a carbon dioxide concentration. The mixed gas is supplied to the initial combustion region, the main combustion region and the post-combustion region in the combustion chamber, and the circulation exhaust gas is supplied to the ash carbonation region.SELECTED DRAWING: Figure 1

Claims

1. A waste incineration method comprising incinerating the waste in an incinerator that burns the waste and discharges it as incinerated ash, The incinerator comprises a combustion chamber for burning the waste, The combustion chamber has, along the flow direction of the waste, an initial combustion region in which initial combustion takes place after the waste has been dried, a main combustion region in which the solid components of the waste and the generated combustible gases are burned, a post-combustion region in which unburned components of the waste are burned to produce incinerated ash, and an ash carbonation region in which carbonation treatment is performed on the incinerated ash. After the circulating exhaust gas supply means branches off at least a portion of the exhaust gas from the incinerator as circulating exhaust gas, the oxygen supply means mixes the circulating exhaust gas with a gas mainly composed of oxygen to produce a mixed gas with a carbon dioxide concentration of 50% or more. The mixed gas is supplied to the initial combustion region, the main combustion region, and the post-combustion region in the combustion chamber, and the circulating exhaust gas is supplied to the ash carbonation region. Waste incineration methods.

2. The ash carbonation region is located at a lower position than the post-combustion region. The waste incineration method according to claim 1.

3. The temperature in the aforementioned ash carbonation region is adjusted to be between 400°C and 600°C. The waste incineration method according to claim 1.

4. The carbon dioxide concentration of the circulating exhaust gas is adjusted to 80% or more. The waste incineration method according to claim 1.

5. A portion of the nitrogen contained in the circulating exhaust gas is separated and removed. The waste incineration method according to claim 1.

6. A waste incineration apparatus equipped with an incinerator that burns waste and discharges it as incinerated ash, A combustion chamber for burning the aforementioned waste, A circulating exhaust gas supply means configured to branch off at least a portion of the exhaust gas from the incinerator as circulating exhaust gas and supply it to the combustion chamber, An oxygen supply means configured to supply a gas mainly composed of oxygen to the combustion chamber, The system includes a gas mixing means that mixes the circulating exhaust gas supplied by the circulating exhaust gas supply means with a gas mainly composed of oxygen supplied by the oxygen supply means to produce a mixed gas with a carbon dioxide concentration of 50% or more, The combustion chamber comprises, along the flow direction of the waste, a drying grate where initial combustion takes place after the waste has been dried, a combustion grate for burning the solid components of the waste and the resulting combustible gases, a post-combustion grate for burning the unburned components of the waste to produce incinerated ash, and an ash carbonation grate where the incinerated ash is subjected to carbonation treatment. The gas mixing means is configured to supply the mixed gas to the drying grate, the combustion grate, and the post-combustion grate. The circulating exhaust gas supply means is configured to supply the circulating exhaust gas to the ash carbonation grate. Waste incineration equipment.

7. The ash carbonation grate is positioned lower than the post-combustion grate, separated by a step. The waste incineration apparatus according to claim 6.

8. The temperature of the aforementioned ash carbonation grate is configured to be adjustable between 400°C and 600°C. The waste incineration apparatus according to claim 6.

9. The circulating exhaust gas is configured to allow adjustment of the carbon dioxide concentration to 80% or more. The waste incineration apparatus according to claim 6.

10. The system further comprises a nitrogen separation means for separating and removing a portion of the nitrogen contained in the circulating exhaust gas. The waste incineration apparatus according to claim 6.

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