Meeting Vision 21 goals with supercritical water gasification (SCWG) of biomass/coal slurries
In the Vapor Transmission Cycle (VTC), a special condensing expander turbine is planned to reduce temperature and pressure for low-temperature cleaning and to maintain quality and combustibility of the fuel vapor for a modern gas turbine. The VTC generates clean fuel gas and steam for gas turbines by feeding water slurries or emulsions above about 25% solids, including coal fines, coal water fuels, biomass, composted municipal refuse, sewage sludge, crumb rubber and pulp and paper wastes in patented HRSG tubes. A commercial method of particle scrubbing is used to improve heat transfer and prevent corrosion and deposition on heat transfer surfaces. Tests were conducted to produce clean fuels for gas turbines and fuel cells via supercritical water gasification (SCWG). The study includes lab-scale testing of composted packer truck refuse and sewage sludge made in an aerobic digester without shredding. A computer-based process simulation model has been prepared that includes material and energy balances that simulate commercial-scale operations of the VTC. Funded by DOE, pilot-scale data produced by General Atomics for sewage sludge shows that SCWG above 640 C and low residence time without an oxidizer can produce a gaseous mixture containing over 25 vol. % hydrogen in methane, carbon monoxide, carbon dioxide and higher light hydrocarbons. Excess hydrogen can be separated for use in fuel cells. Carbon can be separated up to the amount of fixed carbon in the proximate analysis of the solids in the feed. This carbon can be burned in an existing combustion system to help provide the heat required for SCWG, or it can be used to remove pollutants and hydrocarbons from water and air. Test and modeling results will be presented. Preliminary life cycle costs analyses will be presented that establish MSW and sludge disposal fees that improve operating economics over higher-cost fuels. Analyses show that the cost and schedule advantages of natural gas-fired combined cycle systems can be maintained by development. Sensitivity analyses will be presented that show that increases in capital costs can be offset where disposal fees are higher, such as high population areas in the US and Asia.
- Research Organization:
- Environmental Energy Systems Inc. (US)
- OSTI ID:
- 20034309
- Resource Relation:
- Conference: 25th International Technical Conference on Coal Utilization and Fuel Systems, Clearwater, FL (US), 03/06/2000--03/09/2000; Other Information: PBD: 2000; Related Information: In: 25th international technical conference on coal utilization and fuel systems: Proceedings, by Sakkestad, B.A. [ed.], 969 pages.
- Country of Publication:
- United States
- Language:
- English
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