Design and qualification of a bench-scale model for municipal waste-to-energy combustion

ABSTRACT

This paper reports the design and qualification of the first purpose-built, bench-scale reactor system to model the municipal waste-to-energy combustion of fluorinated polymers. Using the principle of similarity, the gas-phase combustion zone of a typical municipal waste-to-energy plant has been scaled down to the bench with a focus on chemical similarity. Chemical similarity is achieved in large part through the use of methanol as a surrogate for municipal solid waste (MSW). Review of prior research shows that methanol is one of the major volatile products expected during MSW thermal conversion in the fuel bed of waste-to-energy plants. Like full-scale waste-energy plants, the design of the bench-scale model includes a flame zone and a post-flame zone. Maintaining steady methanol vapor flow premixed with air to the model reactor system ensures stable combustion resulting in bench-scale CO emission levels comparable to those of full-scale waste-to-energy plants. Since investigation of fluorinated polymer combustion includes trace analysis of exhaust gas for perfluorooctanoic acid (PFOA), qualification testing focused on PFOA collection efficiency. High PFOA collection efficiency (>90%) demonstrated the capability of the reactor system in transporting and absorbing PFOA that may be generated during high-temperature combustion testing of fluorinated polymers. Overall, the bench-scale system is qualified for its intended use to investigate potential generation of PFOA from combustion of fluorinated polymers under conditions representative of waste-to-energy combustion.

Implications: Decision-makers depend on environmental researchers to provide reliable predictions of pollutant emissions from waste combustion of polymers at end of product life. Reliable predictions are especially important with regard to questions about potential PFOA emissions from municipal waste combustion of fluorinated polymers. Results from qualification testing confirm that the novel bench-scale model reactor system is capable of representing gas-phase municipal waste combustion behavior upstream of air pollution control and generating representative exhaust gas samples for off-line trace-level analysis of PFOA.

Acknowledgment

The authors gratefully acknowledge Gary Foggin, Rich McKay, Rich Striebich, Tak Yamada, Larry Bonam, Troy Francisco, and Mike Peo for their guidance and assistance in the design of the reactor system and thank Kelle Vigeland of the City of Spokane for providing the full-scale CO emission performance data depicted in Figure 4.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this paper can be accessed on the publisher’s website

Additional information

Notes on contributors

Robert J. Giraud

Robert J. Giraud completed his doctoral research in environmental engineering at the University of Delaware in 2021 after serving over 30 years as an internal consultant to DuPont and Chemours in environmental engineering and green chemistry. He also teaches green engineering in the University of Delaware Department of Chemical & Biomolecular Engineering.

Philip H. Taylor

Philip H. Taylor founded PTaylor & Associates LLC in 2021 with 5 years of experience as Assistant Vice President of Research at the University of Cincinnati and 28 years of experience in waste combustion as a researcher and group leader in environmental engineering at the University of Dayton Research Institute.

R. Bertrum Diemer

R. Bertrum Diemer joined the faculty of the University of Delaware Department of Chemical & Biomolecular Engineering in 2014 after retiring from DuPont as an Engineering Fellow with over 30 years of service as an internal consultant in the general field of reaction engineering.

Chin-Pao Huang

Chin-Pao Huang holds appointments as the Donald C. Phillips Professor and Francis Alison Professor in the Department of Civil and Environmental Engineering at the University of Delaware in recognition for his over 50 years of research in the thermodynamics and kinetics of environmentally-relevant chemical processes.