Remediation Technologies Screening Matrix, Version 4.0 4.55 High Energy Destruction
(Off-Gas Treatment Technology)
  Description Synonyms Applicability Limitations Site Information Points of Contact
Data Needs Performance Cost References Vendor Info. Health & Safety
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>>3.14 Air Emissions/Off-Gas Treatment

      >>4.55 High Energy Destruction
Introduction>> The high energy destruction process uses high-voltage electricity to destroy VOCs at room temperature.

Description:

Figure 4-55: Typical Low temperature Plasma Reactor The high energy destruction technology is one of many approaches toward decontaminating of air emissions off-gases prior to atmospheric release. The objective of the HEC technology is to provide a standalone, field-portable means of treating off-gases produced during other remedial operations.

High Energy Corona

The High Energy Corona (HEC) process uses high-voltage electricity to destroy VOCs at room temperature. The equipment consists of the following: an HEC reactor in which the VOCs are destroyed; inlet and outlet piping containing process instrumentation to measure humidity, temperature, pressure, contaminant concentration, and mass flow rate; a means for controlling inlet flow rates and inlet humidity; and a secondary scrubber.

The HEC reactor is a glass tube filled with glass beads through which the pretreated contaminated off-gas is passed. Each reactor is 2 inches in diameter, 4 ft long, and weighs less than 20 pounds. A high voltage electrode is placed along the centerline of the reactor, and a grounded metal screen is attached to the outer glass surface of the reactor. A high-voltage power supply is connected across the electrodes to provide 0 to 50 mA of 60-Hz electricity at 30 kV. The electrode current and power depend upon the type and concentration of contaminant.

The technology is packaged in a self-contained mobile trailer that includes gas handling equipment and on-line analytical capabilities. Installation consists of connecting inlet and outlet hoses to the HEC process trailer. Training in the use of the equipment can usually be accomplished well within 1 hour. Failure control is provided by a combination of automated and manually activated means, addressing electrical failure, loss of flow, and loss of VOC containment caused by breakage of the glass reactor vessel. The HEC process can be operated with little, if any, maintenance required. Neither catastrophic failure nor any diminishing in levels of performance have been observed through months of periodic operation in the laboratory. The on-line gas chromatograph and process instruments do require periodic recalibration to ensure data quality.

Tunable Hybrid Plasma Reactor

Researchers at the Massachusetts Institute of Technology (MIT) are investigating plasma chemical processes relevant to the development of a versatile mobile versatile mobile electron-beam driven plasma reactor for efficient on-site decomposition of carbon tetrachloride (CCl4) and other VOCs. The reactor uses a moderate energy electron beam (100-300 keV) that is injected into atmospheric air containing the organic contaminants. The organics are destroyed or oxidized to non-toxic chemicals through their interaction with the electrons and plasma generated from the electron beam. Since a plasma is generated, use of either alternating current (AC) or direct current (DC) electric fields allows a further increase in the electron and gas temperatures to optimize the treatment process. The high degree of tunability of the reactor gave rise to the name tunable hybrid plasma (THP) reactor.

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Synonyms:

NA

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Applicability:

Contaminants that can be treated include most or all VOCs and SVOCs. The potential also exists for treating inorganic compounds, such as oxides of nitrogen and oxides of sulfur. This technique is specifically useful for destroying organics and chlorinated solvents such as trichloroethylene (TCE), tetrachloroethylene (PCE), carbon tetrachloride, chloroform, diesel fuel, and gasoline. Both gas and liquid phase contaminants are treatable.

The THP technology is best suited for treatment of gaseous streams with small concentrations of VOCs especially chlorinated compounds.

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Limitations:

Continued research and development (R&D) is planned to accomplish the following: fully characterize the reactor emissions to complete mass balances; adapt the HEC process to complete real-time control; better understand the physical and chemical phenomena that make the HEC process work; develop larger reactors; and optimize the hardware and packaging associated with the technology for specific, as well as modular or generic, treatment applications.

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Data Needs:

A detailed discussion of these data elements is provided in Subsection 2.2.3. (Data Requirements for Air Emissions/Off-Gases).

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Performance Data:

The HEC technology can destroy more than 99.9% TCE. The technology destroys PCE to a level of 90 to 95%. In preliminary tests with heptane, destruction levels appear to be extremely high, but have not been quantified. When chlorinated VOCs are treated, water containing either sodium hydroxide or baking soda is recirculated in a scrubber to remove acid gases, hydrochloric acid, and chlorine from the reactor effluent. It should also be noted that further contaminant destruction appears likely in this wet scrubber. This is presumably because of strong gaseous oxidants that exit the HEC reactor. Typical outlet properties would be nondetectable concentrations of TCE, ozone, hydrochloric acid, phosgene, and chlorine, with up to 1 ppmv NOx (below regulatory limits). Air exits the HEC process at temperatures of 100 C or lower or slightly above ambient temperature if a wet scrubber is used. A scrub solution (containing less than 10-wt% sodium chloride in water) is produced when chlorinated VOCs are treated.

One reactor processes up to 5 scfm of soil off-gas. The HEC field-scale process demonstrated at Savannah River uses 21 HEC reactors in parallel to treat up to 105 scfm of contaminated off-gas. A typical application will involve an inlet stream containing 1,800 ppm of TCE in humid air at 10 to 20 C. Power input is typically 50 to 150 W/scfm being processed. For dry inlet streams, deionized water is added as steam to produce an inlet humidity (hr) of 60 to 80%. Less than 20 mL per minute of water is required to humidify a completely dry stream at a flow of 105 scfm. For water-saturated inlet streams, the stream is preheated (using electric heaters) to lower the hr from 100% to 80%. In many cases, the vapor-extraction blower associated with retrieving the VOCs from soil will sufficiently preheat the soil off-gas to 80% or lower so that no further preheating is required.

Discussions with manufacturers/licensees have been initiated with the belief that HEC is now ready for commercial availability. The 105-scfm field prototype is available now for commercial testing and evaluation. Pacific Northwest Laboratory (PNL) is continuing R&D to improve and scale the technology. Scaleup to 50 scfm per reactor seems feasible for extremely large applications.

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Cost:

Initial outlay for a 105 scfm process, the prototype field treatment system, is $50,000. As with any other technology, large-scale production and customization would significantly reduce costs, perhaps to as low as $20,000. Labor requirements are projected as 0.25 fulltime equivalent. Energy requirements are $27 per day, or roughly $0.35 per pound of contaminant. Total cost is roughly $10 per pound of contaminant, including a 25% contingency to account for any unknown additional costs. Although maintenance costs are minimal, the total cost figure assumes 8% downtime and a capital payback period of 6 months.

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References:

DOE-RL, 1993. Technology Name: High-Energy Corona, Technology Information Profile (Rev. 2) for ProTech, DOE ProTech Database, TTP Reference No.: RL-3211-01.

DOE, 1994. Technology Catalogue, First Edition. February.

TNA-II OTD/OER Crosswalk Worksheet, 1992, "High-Energy Corona for Destruction of VOCs in Process Off Gases," The 1993 Technology Needs Crosswalk Report, Vol. 3, Appendix H, TTP Reference No.: RL-3211-01, Richland, WA, TRL009.

Virden, J.W., W.O. Heath, S.C. Goheen, M.C. Miller, G.M. Mong, and R.L. Richardson, 1992. "High-Energy Corona for Destruction of Volatile Organic Contaminants in Process Off-Gases," in Proceedings of Spectrum '92 International Topical Meeting on Nuclear and Hazardous Waste Management, Vol. 2, pp. 670-673, 23-27 August 1992, Boise, ID.

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Site Information:

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Points of Contact:

General FRTR Agency Contacts

Technology Specific Web Sites:

Government Web Sites

Non Government Web Sites

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Vendor Information:

A list of vendors offering Air Emission/Off-Gas Treatment is available from  EPA REACH IT which combines information from three established EPA databases, the Vendor Information System for Innovative Treatment Technologies (VISITT), the Vendor Field Analytical and Characterization Technologies System (Vendor FACTS), and the Innovative Treatment Technologies (ITT), to give users access to comprehensive information about treatment and characterization technologies and their applications.

Government Disclaimer

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Health and Safety:

Hazard Analysis

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