A number of metallic and ceramic materials were exposed in both supercritical and subcritical zon... more A number of metallic and ceramic materials were exposed in both supercritical and subcritical zones of the effluent path in a pilot supercritical water oxidation (SCWO) unit which had been developed for treatment of hazardous wastes. The test coupons as well as several components removed from the reactor and from effluent sections of the plant were evaluated during and upon completion of a recent process demonstration program. This paper summarizes results of the materials performance evaluation. Typical materials evaluated after exposure in the SCWO environment (T > 374 C) included high-nickel alloys such as Alloys 625, 718, C-276, and 750, titanium and its alloys, platinum and its alloys, and a few ceramics. Some of these materials as well as titanium were also exposed in the subcritical environment (T < 374 C). Incidence of corrosion experienced during the SCWO demonstration program are illustrated in terms of metal loss, incidence of localized corrosion such as pitting and...
Proceeding of Physical Chemistry of Aqueous Systems: Meeting the Needs of Industry, 1995
Sodium chloride-sodium sulfate is one of the most commonly encountered mixed salt systems in pros... more Sodium chloride-sodium sulfate is one of the most commonly encountered mixed salt systems in prospective applications of zupercritical water oxidation. When present alone, either salt may readily be precipitated in sotd form With mixhres of these salts, however, eutectic-like phenome,na give rise to dense high salt liquids over wide teryeraturs langoS, which can have serious ramifications oo process design and performance. The prese,nt paper illustrates the phase behavior of the tenrary NaCl-NarSO+-HzO system at 250 and 225 bar and in adilition describes the effect of "noncondensible" gases such as tle oxidant on the system
A process for water oxidation of combustible materials in which during at least a part of the oxi... more A process for water oxidation of combustible materials in which during at least a part of the oxidation corrosive material is present and makes contact with at least a portion of the apparatus over a contact area on the apparatus. At least a portion of the contact surface area comprises titanium dioxide coated onto a titanium metal substrate. Such ceramic composites have been found to be highly resistant to environments encountered in the process of supercritical water oxidation. Such environments typically contain greater than 50 mole percent water, together with oxygen, carbon dioxide, and a wide range of acids, bases, and salts. Pressures are typically about 27.5 to about 1000 bar while temperatures range as high as 700.degree. C. The ceramic composites are also resistant to degradation mechanisms caused by thermal stresses.
The process of Supercritical Water Oxidation (SCWO) is approaching terrestrial commercialization ... more The process of Supercritical Water Oxidation (SCWO) is approaching terrestrial commercialization for the destruction of toxic and hazardous waste chemicals. The technology appears promising for use in space applications, where its primary functions would be aqueous waste treatment, potable water product, and possibly facility atmosphere purification. The present paper discusses some of the considerations for the use of SCWO in space facilities.
ABSTRACT A method is described for substantially completely oxidizing combustible materials in wh... more ABSTRACT A method is described for substantially completely oxidizing combustible materials in which an aqueous stream bearing the combustible materials is reacted in the presence of an oxidant comprising diatomic oxygen and at a temperature greater than the critical temperature of water and at a pressure greater than about 25 bar, within a reactor for a period of less than about 5 minutes to produce a reaction product stream, wherein the reaction is initiated in the presence of a rate enhancer comprising at least one oxidizing agent in addition to said oxidant selected from the group consisting of ozone, hydrogen peroxide, salts containing persulfate, salts containing permanganate, nitric acid, salts containing nitrate, oxyacids of chlorine and their corresponding salts, hypochlorous acid, salts containing hypochlorite, chlorous acid, salts containing chlorite, chloric acid, salts containing chlorate, perchloric acid, and salts containing perchlorate.
Journal of Advanced Oxidation Technologies, Dec 31, 2006
Abstract: Due to the extreme conditions under which water becomes a supercritical fluid (374 C, 2... more Abstract: Due to the extreme conditions under which water becomes a supercritical fluid (374 C, 221 bar), most research and applications of supercritical water to date have been associated with chemically destructive processes. Supercritical water oxidation (SCWO), ...
A number of metallic and ceramic materials were exposed in both supercritical and subcritical zon... more A number of metallic and ceramic materials were exposed in both supercritical and subcritical zones of the effluent path in a pilot supercritical water oxidation (SCWO) unit which had been developed for treatment of hazardous wastes. The test coupons as well as several components removed from the reactor and from effluent sections of the plant were evaluated during and upon completion of a recent process demonstration program. This paper summarizes results of the materials performance evaluation. Typical materials evaluated after exposure in the SCWO environment (T > 374 C) included high-nickel alloys such as Alloys 625, 718, C-276, and 750, titanium and its alloys, platinum and its alloys, and a few ceramics. Some of these materials as well as titanium were also exposed in the subcritical environment (T < 374 C). Incidence of corrosion experienced during the SCWO demonstration program are illustrated in terms of metal loss, incidence of localized corrosion such as pitting and...
Proceeding of Physical Chemistry of Aqueous Systems: Meeting the Needs of Industry, 1995
Sodium chloride-sodium sulfate is one of the most commonly encountered mixed salt systems in pros... more Sodium chloride-sodium sulfate is one of the most commonly encountered mixed salt systems in prospective applications of zupercritical water oxidation. When present alone, either salt may readily be precipitated in sotd form With mixhres of these salts, however, eutectic-like phenome,na give rise to dense high salt liquids over wide teryeraturs langoS, which can have serious ramifications oo process design and performance. The prese,nt paper illustrates the phase behavior of the tenrary NaCl-NarSO+-HzO system at 250 and 225 bar and in adilition describes the effect of "noncondensible" gases such as tle oxidant on the system
A process for water oxidation of combustible materials in which during at least a part of the oxi... more A process for water oxidation of combustible materials in which during at least a part of the oxidation corrosive material is present and makes contact with at least a portion of the apparatus over a contact area on the apparatus. At least a portion of the contact surface area comprises titanium dioxide coated onto a titanium metal substrate. Such ceramic composites have been found to be highly resistant to environments encountered in the process of supercritical water oxidation. Such environments typically contain greater than 50 mole percent water, together with oxygen, carbon dioxide, and a wide range of acids, bases, and salts. Pressures are typically about 27.5 to about 1000 bar while temperatures range as high as 700.degree. C. The ceramic composites are also resistant to degradation mechanisms caused by thermal stresses.
The process of Supercritical Water Oxidation (SCWO) is approaching terrestrial commercialization ... more The process of Supercritical Water Oxidation (SCWO) is approaching terrestrial commercialization for the destruction of toxic and hazardous waste chemicals. The technology appears promising for use in space applications, where its primary functions would be aqueous waste treatment, potable water product, and possibly facility atmosphere purification. The present paper discusses some of the considerations for the use of SCWO in space facilities.
ABSTRACT A method is described for substantially completely oxidizing combustible materials in wh... more ABSTRACT A method is described for substantially completely oxidizing combustible materials in which an aqueous stream bearing the combustible materials is reacted in the presence of an oxidant comprising diatomic oxygen and at a temperature greater than the critical temperature of water and at a pressure greater than about 25 bar, within a reactor for a period of less than about 5 minutes to produce a reaction product stream, wherein the reaction is initiated in the presence of a rate enhancer comprising at least one oxidizing agent in addition to said oxidant selected from the group consisting of ozone, hydrogen peroxide, salts containing persulfate, salts containing permanganate, nitric acid, salts containing nitrate, oxyacids of chlorine and their corresponding salts, hypochlorous acid, salts containing hypochlorite, chlorous acid, salts containing chlorite, chloric acid, salts containing chlorate, perchloric acid, and salts containing perchlorate.
Journal of Advanced Oxidation Technologies, Dec 31, 2006
Abstract: Due to the extreme conditions under which water becomes a supercritical fluid (374 C, 2... more Abstract: Due to the extreme conditions under which water becomes a supercritical fluid (374 C, 221 bar), most research and applications of supercritical water to date have been associated with chemically destructive processes. Supercritical water oxidation (SCWO), ...
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