| 摘要 |
PROBLEM TO BE SOLVED: To improve stress corrosion cracking resistance in high temp. high pressure water in a supercritical state or a subcritical state by controlling the concentration of dissolved oxygen in water to equal to or below a specific value and decomposing an organic material in the presence of a steam reforming catalyst. SOLUTION: The organic material is decomposed in the presence of the steam reforming catalyst by controlling the concentration of dissolved oxygen in water to <= about 200 ppb, preferably <= about 160 ppb. That is, a slurried plastic in a waste slurry tank 1 is fed to a reaction tube 4 for supercritical water by a high pressure pump 2 for supercritical water and is decomposed in water having <=200 ppb dissolved oxygen concentration in the presence of the steam reforming catalyst. Next, the slurried plastic is fed to a reaction tube 6 for subcritical water and decomposed in the subcritical water. Next, the cooling by a cooler 7 and the neutralization in a neutralization vessel 2 are performed. As a result, the generation of the stress corrosion cracking is prevented and for example, polyvinyl chloride is almost completely decomposed. |
