19 May 2015
Posted in Center Information
PI: Dr. Skip Ingley & Dr. Jacob Chung, UF
According to the U.S. Environmental Protection Agency, 53.8% of the municipal solid waste (MSW) which is around 164.3 million tons were discarded in landfills in the United States in 2012. The recoverable energy of MSW in landfills is considerable, so it makes the MSW a potential energy source once it can be converted into a useful energy form.
The main objective of this study was to investigate the thermochemical conversion of waste materials such as MSW, plastics, rubber associated with tires, woody biomass, and sewage sludge into gaseous fuels using a steam gasification process. The system investigated used high temperature steam as the gasifying agent in an oxygen free environment to decompose the feedstock completely into pure synthesis gas (syngas). Since the process does not involve any air, the syngas is free of nitrogen which usually dilutes and lowers the heating value of the syngas which is the case of the air-participating partial combustion and partial gasification processes.
In the experiment, the gas generation rate and the chemical composition of the gas were measured and evaluated with respect to time in order to study the dynamics of the gasification process. Minor species in the produced syngas were also analyzed to investigate any environmental effects that might be associated with the steam gasification process. 2
A bench scale experimental apparatus was used to produce a high quality syngas that was then analyzed using gas chromatography and a mass spectrometry. The results showed that the syngas contained high concentrations of H2, around 50-60% by volume, and the heating values of the syngas reached a magnitude of 8-10 MJ/m3 for all four types of feedstock. This is approximately 2.5 times more by weight and 1.6 times more by volume compared to the results found in the year one study using the air-participating gasification system. Also, minor species was detected successfully. These results were compared to conventional incineration and air-participating gasification systems. Additionally, a thermodynamic equilibrium model was developed and successfully verified by the experimental results.