Portland State University. Department of Civil and Environmental Engineering
Gwynn R. Johnson
Date of Award
Master of Science (M.S.) in Civil & Environmental Engineering
Civil and Environmental Engineering
Plasma jets, Refuse and refuse disposal -- Management, Air -- Pollution -- Prevention, Municipal engineering
The goal of this project was to develop a prototype plasma gasification system to treat municipal solid waste (MSW) with minimal regulated emissions in a footprint small enough to be transported for a wide range of applicability. This project started with a review of current MSW treatment methods and of the emissions produced from thermal breakdown of MSW. A review of air quality regulations and emission control technologies was then used to select the emission control systems to be used for a small-scale plasma gasification system.
This plasma gasification system began with a plasma torch and cooling system being designed, built, and tested with various electrode materials and designs. The torch was tested using compressed air, nitrogen, and a mixture of argon and hydrogen. Tungsten was chosen for the positive electrode and copper for the negative electrode, with compressed nitrogen as the process gas. A gasification chamber was designed and built to handle the molten material and act as a platform for the torch-centering device, exhaust port, and viewing window. Several emission control systems were built based on expected pollutants of MSW decomposition. These controls include a particle separator, catalytic converter and a packed column scrubber. Gas and atmospheric sensors were then programmed and installed in the exhaust gas stream.
This prototype plasma gasification system was built with the intent of testing various materials one at a time and measuring the emissions produced. This data would then have been used to modify and improve the emission controls used to eliminate or capture any contaminants in the syngas, with the intent of having the syngas be a mixture of only hydrogen and carbon monoxide. Later additions would include a fuel cell to be used with the hydrogen, a heat exchanger and turbine to recover energy from the heat produced, and material recovery systems for the contaminants detected.
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Male, Keith, "Small Scale Plasma Gasification of Municipal Solid Waste" (2021). Civil and Environmental Engineering Master's Project Reports. 55.