Oxidation of phenolics in supercritical water. Quarterly technical progress report, March 1, 1994--May 31, 1994

Technical Report · Thu Sep 01 04:00:00 EDT 1994

DOI:https://doi.org/10.2172/10182479· OSTI ID:10182479

Savage, P E

An environmental hazard associated with coal liquefaction and gasification is the generation of aqueous waste streams containing phenolics and carcinogenic organics such as polynuclear aromatics. Oxidation in supercritical water (SCW) is an emerging technology for the ultimate destruction of phenolics and other organics in waste water streams. SCW oxidation involves the oxidation of organics in an aqueous medium at temperatures between 400-650{degrees}C and pressures around 250 atm. These conditions exceed the thermodynamic critical point of water, hence the water is said to be supercritical. Wastes can be converted by SCWO to benign products: carbon is converted to CO{sub 2}, hydrogen to H{sub 2}O, and nitrogen to N{sub 2} or N{sub 2}O (but not NO{sub X}). SCWO possesses several attractive features. (1) The effluents from the SCWO process can be collected or held in a recycle loop so the process can be easily {open_quotes}bottled up{close_quotes} with no uncontrolled emissions should an upset occur. (2) The oxidation reaction is exothermic, so it is possible to operate the SCWO reactor in an autothermal mode. That is, the oxidation of the organic material in the aqueous stream liberates sufficient heat to maintain the elevated reactor temperature and also preheat the feed. Thus, after start-up, the process would not require an external energy source and could even be used to produce energy provided the organics content in the feed stream was sufficiently high. (3) Operating at supercritical conditions also provides a single, homogeneous fluid phase in the reactor. Indeed, water above its critical point has a high solubility for organics, and it is totally miscible with oxygen. (4) The temperature in SCWO is high enough to provide rapid reaction rates but not so high that alloys begin to lose their mechanical strength. Thus, the oxidation of organics goes essentially to completion in a very short time (a few seconds).

• Research Organization: Michigan Univ., Ann Arbor, MI (United States). Dept. of Chemical Engineering
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: FG22-92PC92536
• OSTI ID: 10182479
• Report Number(s): DOE/PC/92536--T7; ON: DE94018848
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010800
COAL GASIFICATION
COAL LIQUEFACTION
OXIDATION
PHENOLS
PROGRESS REPORT
PURIFICATION
WASTE MANAGEMENT
WASTE WATER