| Countercurrent gasification is a member of a class of thermal remediation processes which includes incineration and pyrolysis, and is an outgrowth of in-situ underground coal gasification. Remediation of waste using this processs consits of combining char and waste, followed by gasifyng the mixture. The organic components in the waste are converted to a synthesis gas, primarily CO and H{dollar}sb2{dollar}, and only a small amount of the char is consumed.; In this dissertation, an evaluation of the process for remediation of an industrial waste, an oily sludge which consists of styrene and petroleum wastes, was undertaken. The factors considered were: (1) Understanding of the physical and chemical basis for treatment; (2) Feasibility for the process; (3) Effectiveness for the process; (4) Potential for commercialization.; This research showed that the destruction of the sludge was feasible and effective. Specifically, the sludge was immobilized on the char and effectively made manageable for processing. The optimum loading of oil on the char was found to be about 25% by weight. The gasification of the sludge produced a clean-burning synthesis gas, containing the expected products, CO, CO{dollar}sb2{dollar}, H{dollar}sb2{dollar}O, H{dollar}sb2{dollar} and CH{dollar}sb4{dollar}, and only small amounts of short chain hydrocarbons. The char product was found to be reusable for at least four cycles of remediation.; Thermodynamic analysis of the process predicts that of the available energy content in the system to be gasified, a maximum of 53% can be recovered in the form of synthesis gas. Of the remainder, 35% will be converted to waste heat and 12% will be sensible heat. The analysis also predicts the composition of the gas product, and the observed composition was found to differ somewhat from that predicted.; The results presented indicate that the commercialization potential of the process is favorable for the application studied. |
