Steam Reforming

Sandia National Laboratories



Description

Steam reforming is a technology designed to destroy halogenated solvents (such as carbon tetrachloride, CCl4, and chloroform, CHCl3) adsorbed on activated carbon by reaction with superheated steam (steam reforming) in a commercial reactor (the Synthetica Detoxifier).

Drums of granular activated carbon (GAC), previously loaded with CCl4 and CHCl3, are desorbed by exposure to 300 °C steam using an experimental thin film sensor to follow the desorption. The CCl4- and CHCl3-laden steam is then passed through a moving bed evaporator, which consists of a bed of ceramic spheres coated with alkali base. At the 600 °C operating temperature of the evaporator, the chlorocarbons are efficiently decomposed, releasing hydrochloric acid (HCl), which is neutralized by the alkali base coated spheres. As the spheres settle to the bottom of the evaporator, spent base and chloride salts formed by the neutralization of HCl are mechanically scraped off of the spheres. At the bottom of the evaporator, spheres are removed and transported to the top of the evaporator by a bucket elevator, where they are coated with fresh base and reinjected into the evaporator.

The effluent steam stream from the evaporator is fed to a high-temperature (1200 °C) reaction chamber of the Synthetica Detoxifier, where any organic fragments released in the evaporator are destroyed. Any HCl released in the detoxifier is removed by adsorption and neutralization by Selexsorb, a commercial adsorbent. Finally, the effluent from the reactor is passed through a catalytic converter, where carbon monoxide (CO) and hydrogen (H2) are converted to carbon dioxide (CO2) and water.


Technical Performance

This technology can be used with multiple feed streams and can destroy any organic that can be gasified by exposure to 600 °C steam.

Drum Feeder. Liquid and solid wastes in drums are gasified in the drum feeder at an operating temperature of 300 °C.

Moving Bed Evaporator. Liquid waste streams are flash vaporized at 600 °C operating temperature.

Detoxifier. The detoxifier can handle a wide variety of waste forms. Operation is completely automated and the unit (4 ft x 5 ft x 7 ft) is easily transportable. Effluents are expected to consist principally of CO2 and water, traces of H2, ethane (CH4), CO, nitric oxide (NO), and nitrogen dioxide (NO2). The high-temperature reaction chamber of the detoxifier operates at 1200 °C.

Destruction efficiencies are greater than 99.99% and GAC reactivation has been demonstrated for the Synthetica system. One ton/day of chlorocarbons can be processed.

Because steam reforming is not a combustion process, fuel and air are not used, and products of incomplete combustion are not generated.

Cost. The estimated cost breakdown is the detoxifier, $325K; the drum feeder, $50K; and the moving bed evaporator, $165K. The cost of other peripherals is estimated to be $150K. Daily operating and maintenance costs are estimated at $600. Life cycle costs are $340K (5 years) and $270K (10 years). Steam reforming is approximately 75% less expensive than offsite thermal regeneration of GAC.


Projected Performance

A Cooperative Research and Development Agreement between Synthetica Technologies and SNL will support studies of alternative heating methods (e.g., microwave heating) for the detoxifier, use of steam reforming catalysts in the detoxifier, and the conversion of the Synthetica gas effluent from the detoxifier into light hydrocarbons using Fischer-Tropsch catalysts.


Waste Applicability

Steam reforming is applicable to the treatment of halogenated solvents adsorbed on GAC.


Status

The system is currently available. An improved moving bed evaporator will be available in 1994.


Regulatory Considerations

The spent slurry and salts generated in the moving bed evaporator would be regulated as wastes if toxic or inorganic materials are constituents of these wastes. In such cases, further treatment of the spent slurry and salts may be required prior to disposal. Because of the emissions from the detoxifier, air permits for its operation are routinely obtained. Resource Conservation and Recovery Act (RCRA) and Nuclear Regulatory Commission (NRC) permits may also be required for treatment of radioactive or hazardous wastes.


Potential Commercial Applications

This technology has wide application for destruction of a wide variety of wastes, such as paint residues, epoxy explosives, benzene, and low-level radioactive wastes.


Baseline Technology

Offsite thermal regeneration of GAC.


Intellectual Property Rights

Patent Ownership: Synthetical Technologies, Inc. Patent No.: 4,874,587


For more information, please contact:

DOE/OTD Environmental Technology
Information Service
(800) 845-2096

DOE Program Manager
David Biancosino
EM-551, Trevion II
U.S. Department of Energy
Washington, DC 20585
(301) 903-7961

Principal Investigator
Jeremy Sprung
Sandia National Laboratories
P.O. Box 5800, Org. 6602
Albuquerque, NM 87185-5800

Industrial Partnership
Synthetica Technologies, Inc.

References

  1. Galloway, T. R., ``Destroying Hazardous Waste On Site--Avoiding Incineration,'' Environ. Progress, 8, 176 (1989).

  2. Galloway, T. R., ``Thermal Treatment with the Thermolytica Detoxifier,'' Innovative Waste Treatment Technology Series, Vol. 1, Thermal Processes, H. M. Freeman, Ed., Technomic Publishing Co., Lancaster, PA, 1989.

  3. Galloway, T. R., ``The Role of Steam in Lowering PICs in a Thermal Detoxifier,'' Proceed. AIChE Annual Meeting, San Francisco, CA, Nov. 5-10, 1989.

  4. Sutton, W. H., et al., Eds., ``Microwave Processing of Materials,'' Materials Research Society Proceedings, Vol. 24, Materials Research Society, Pittsburgh, PA, 1988.

  5. Nimlos, M. and T. A. Milne, ``Direct Mass Spectrometric Studies of the Photo-Thermal-Catalytic Destruction of Hazardous Wastes: Pyrolysis and Catalytic Steam Reforming of Chlorinated Hydrocarbons,'' Environ. Sci. Technol. (to be published).

  6. Skocypec, R. D., and R. E. Hogan, ``Investigations of a Direct Catalytic Adsorption Reactor for Hazardous Waste Destruction,'' Proceed. 1990 ASME Intl. Solar Energy Conf., Miami, FL, April 1-4, 1990, p. 167.

  7. Private Communication, J. T. Richardson, Dept. Chem. Eng., University of Houston, 1989.

  8. Rostrup-Nielsen, J. R., ``Catalytic Steam Reforming,'' Catalysis Science and Technology, J. R. Anderson and M. Boudart, Eds., Springer-Verlag, New York, 1984, p. 1.

  9. Johnson, J. L., ``Fundamentals of Coal Gasification,'' and D. Hebden and H. J. F. Stroud, ``Coal Gasification Processes,'' Chemistry of Coal Utilization, 2nd Suppl. Vol., M. A. Elliott, Ed., Wiley, New York, 1981, pp. 1491-1752.

  10. Tyner, C. E., ``Application of Solar Thermal Technology to the Destruction of Hazardous Wastes,'' Solar Energy Materials, 21, 113 (1990).

  11. Richardson, J. T. and S. A. Paripatyadar, ``Carbon Dioxide Reforming of Methane with Supported Rhodium,'' Appl. Catal., 61, 293 (1990).

  12. Oppelt, E. T., ``Incineration of Hazardous Waste, A Critical Review,'' JAPCA, 37, 558 (1987).


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