(Frequency-Tunable Pulse Combustion System)
The Sonotech, Inc., frequency-tunable pulse combustion system (Sonotech system) is designed to significantly improve batch- and continuous-mode combustion or thermal processes such as incineration by creating large-amplitude, resonant pulsations inside the combustion chamber. This technology can be applied to new or existing combustion systems. The technology is used in fossil fuel combustion devices, residential natural gas furnaces, and industrial combustion systems. It should prove similarly beneficial to hazardous waste incineration and soil remediation applications.
The Sonotech system (see photograph below) consists of an air inlet, a combustor section, a tailpipe, a control panel, and safety features. This system is designed to improve an incinerator's performance by (1) increasing mixing rates between the fuel and air, (2) increasing mixing rates between reactive gas pockets and ignition sources, and (3) increasing rates of heat and mass transfer between the gas and the burning waste. These improvements should (1) reduce the amount of excess air required to completely burn the waste, (2) increase destruction and removal efficiencies (DRE) of principal organic hazardous constituents, (3) minimize the formation of products of incomplete combustion, and (4) eliminate or minimize detrimental emissions or "puffs."
Frequency-Tunable Pulse Combustion System Installed
at EPA's Incineration Research Facility
The Sonotech system has achieved sound amplitudes as high as 170 decibels and frequencies of 100 to 500 hertz within the combustion chamber. The high frequencies and velocities of these gas oscillations help mix the gases in the chamber and thus reduce or eliminate stratification effects.
The Sonotech system can function alone or as a supplemental retrofit to an existing combustion system. In the latter application, the frequency-tunable pulse combustion system can supply as little as 2 to 10 percent of the total energy requirements. The total fuel supplied to the main burner and the Sonotech system should be less than the amount of fuel supplied to the main burner before retrofitting.
This technology can be used with any material that can be treated in a conventional incinerator. Sonotech, Inc., believes that the technology is ready for incineration of hazardous, municipal, and medical waste.
This technology was accepted into the SITE Demonstration Program in 1992. The 6-week demonstration evaluated whether the technology improved the performance of a larger scale incineration system. To meet this goal, the pilot-scale rotary kiln incinerator at EPA's Incineration Research Facility (IRF) in Jefferson, Arkansas was retrofit with a Sonotech system. The demonstration took place from September to October 1994. The retrofit incinerator was used to treat coal- and oil-gasification wastes, traditionally incinerated with conventional technology. The Technology Capsule (EPA/540/R-95/502a) is available from EPA. More detailed results will be available from EPA in early 1997.
The Sonotech system increased the incinerator waste feed rate capacity by 13 to 21 percent compared to conventional combustion. As the demonstration waste had significant heat content, the capacity increase was equivalent to a reduction in the auxiliary fuel needed to treat a unit mass of waste from 21,100 British thermal unit/pound (Btu/lb) for conventional combustion to 18,000 Btu/lb for the Sonotech system. Visual observations indicated improved mixing in the incinerator cavity with the Sonotech system operating.
Benzene and naphthalene DREs were greater than 99.99 percent. The average concentration of carbon monoxide exiting the afterburner, corrected to 7 percent oxygen, decreased from 20 parts per million (ppm) with conventional combustion to 14 ppm with the Sonotech system. The average afterburner exit nitrogen oxides concentration, corrected to 7 percent oxygen, decreased from 82 ppm with conventional combustion to 77 ppm with the Sonotech system. Average soot emissions exiting the afterburner, corrected to 7 percent oxygen, were reduced from 1.9 milligrams per dry standard cubic meter (mg/dscm) for conventional combustion to less than 1.0 mg/dscm with the Sonotech system. Total system combustion air requirements, determined from stoichiometric calculations, were lower with the Sonotech system in operation.
EPA PROJECT MANAGER:
Marta K. Richards
U.S. EPA
National Risk Management Research Laboratory
26 West Martin Luther King Drive
Cincinnati, OH 45268
513-569-7692
Fax: 513-569-7676
TECHNOLOGY DEVELOPER CONTACT:
Ben Zinn
Sonotech, Inc.
3656 Paces Valley Road
Atlanta, GA 30327
404-894-3033
Fax: 404-894-2760