Gasification is a process through which solid and liquid carbonaceous materials are converted to a combustible product gas consisting of a mixture of CO, CO 2 , H 2 , and CH 4 (and N 2 if air is used as a source of oxygen). The product gas can be combusted to provide energy or can be used for a variety of industrial applications. Gasification is a potentially cleaner and more efficient means of energy production than combustion of solid fuels. While gasification has been extensively researched, specifically coal gasification and to a lesser extent biomass gasification, a niche application of gasifying byproducts from the cattle rendering and meatpacking industries is gaining interest. Because of recent outbreaks of mad cow disease in Canada and the United States, regulations on the use of specified risk material (SRM), meat and bone meal, and entire carcasses are becoming more stringent in Canada and in the future are expected to become more stringent in the United States as well. One possible disposal option for these materials is gasification. In this study, four byproduct materials from the cattle rendering and meatpacking industries were gasified in a bench-scale gasification unit at Penn State's Energy Institute. The feed materials included meat and bone meal, cow carcasses, and two types of SRMs. The feed samples were gasified at 1000 °C with nitrogen and steam carrier gasses. The composition of the product gas produced during the gasification reaction was analyzed using gas chromatography. A material balance of the reaction was conducted to assess reliability of the results. Gas production, hydrogen yields, other combustible gas yields, and energy densities show that gasification can potentially serve as a means of carcass and SRM disposal and energy production in the cattle rendering and meatpacking industries.
This study was performed to demonstrate the technical viability of cofiring animal-tissue biomass (ATB) in a coal-fired fluidized-bed combustor (FBC) as an option for disposing of specified risk materials (SRMs) and carcasses. This is a potential option for beneficially utilizing SRMs and carcasses that must be removed from the food chain, allowing them to be used as an energy feedstock rather than disposing them via landfilling or incineration. The purpose of this study was to assess the technical issues of feeding/combusting ATB and not to investigate prion deactivation/pathogen destruction. Overall, the project successfully demonstrated that carcasses and SRMs can be cofired with coal in a bubbling FBC. Feeding ATB into the FBC did, however, present several challenges. Specifically, handling/feeding issues resulting from the small scale of the equipment and the extremely heterogeneous nature of the ATB were encountered during the testing. Feeder modifications and an overbed firing system were necessary. Through statistical analysis, it was shown that the ATB feed location had a greater effect on CO emissions, which were used as an indication of combustion performance, than the fuel type due to the feeding difficulties. Baseline coal tests and tests cofiring ATB into the bed were statistically indistinguishable. Fuel feeding issues would not be expected at the full scale since full-scale units routinely handle low-quality fuels. In a full-scale unit, the disproportionate ratio of feed line size to unit diameter would be eliminated thereby eliminating feed slugging. Also, the ATB would either be injected into the bed, thereby ensuring uniform mixing and complete combustion, or be injected directly above the bed with overfire air ports used to ensure complete combustion. Therefore, it is anticipated that a demonstration at the full scale, which is the next activity in demonstrating this concept, should be successful. As the statistical analysis shows, emissions cofiring ATB with coal would be expected to be similar to that when firing coal only.
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