RDF Gasification in an Atmospheric, Air-Blown, Circulating Fluid-Bed Gasifier

The largest commercial RDF gasification plant in Europe is believed to be the system built in 1992 in Italy that produces low-energy gas at a feed rate of 180 t/day of RDF, which is obtained from 600 t/day of MSW (Barducci et ah, 1995, 1996). The hot product gas from the fluid-bed gasifiers is burned in an on-site boiler or is used as industrial fuel. The flue gas from the boiler is cleaned in a three-stage dry scrubber system before being exhausted through the stack. The steam raised in the boiler drives a 6.7-MW condensing steam turbine. Alternatively, the product gas is supplied as fuel to a neighboring cement plant. When the plant is eventually completed by addition of other gasification units, the facility will have the capacity to process 1300 t/day of MSW. The gasification system for this plant was developed by TPS Termiska Processer AB (Morris, 1996). It consists of two circulating fluid-bed gasifiers, each of 54 GJ/h capacity. A downstream cleanup process for the hot product gas is expected to be installed in future plant additions. In this process, the tars in the product gas are catalytically cracked at about 900°C in a dolomite — containing vessel located immediately downstream of the gasifier, and the particulates and alkalis are removed. This is expected to eliminate equipment contamination and filter clogging by tar condensation as the product gas is cooled. The TPS technology is expected to be used for similar projects in The Netherlands and the United Kingdom, and also for the biomass-fueled, integrated gasification, combined-cycle (BIGCC) power plant in Brazil. The B1GCC plant is expected to demonstrate the commercial viability of producing electric power from eucalyptus in an advanced technology plant of 30 MW capacity (see Section V, E).