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Show higher sulfur removal. Figure 9b shows the dramatic effect a sorbent change can have under similar operating conditions. A number of waste fuels have also been MSFB pilot and commercial systems. These tests investigated the combustion efficiency, CO and the emission of the primary pollutants, NOx and S02. A few of the test results are described below. Pilot Tests. Co-firing of paint sludge and plastic wastes with coal has been studied in Battelle's 1 x 10 Btu/hr pilot plant. The coal used in this combustion study was a medium sulfur Ohio No.5 coal containing approximately 1.9% sulfur. The results of these tests are summarized in Table 1. Combustion efficiencies of 97 to 98% were maintained under co-firing operations with both paint sludge and plastic. NOx emissions for all three tests were controlled through adjustment of primary zone stoichiometry. This method of control was effective even when cofiring with paint sludge containing over 4% nitrogen. Calcium contained in both the paint sludge and plastics are credited with lowering S02 emissions for the same limestone Ca/S feed ratio. The plastic contained as much as 10% calcium, whereas the paint sludge contained over 6% calcium. Carbon monoxide emissions were lower for the sludge/coal mixture than for coal alone. This appears to be due to the higher volatile content of the paint sludge. In contrast, the carbon monoxide emissions for the plastic/coal mixture were greater than for the coal alone. The hard to burn carbon in the plastic char is credited for the higher CO emissions. In general, relatively high CO levels were common to all tests conducted in this 6 inch diameter pilot-scale system. The combustor did not have the oxidizing zone height available on fullscale commercial systems to ensure complete combustion of the CO. Commercial Tests. Municipal waste in the form of refuse derived fuel (RDF) pellets were test fired in a full-scale MSFB system at Kerry Coop in Listowell, Ireland. Carbon monoxide ranged from 30 to 180 ppm while NOx ranged from 60 to 80 ppm. Although sulfur dioxide was not controlled, emissions averaged 160 ppm during the test. Although carbon burnout did not appear to be a problem, a longer test would be required to fully evaluate the effects of this fuel on overall combustion efficiency. SUMMARY Multisolid fluidized bed combustion systems are capable of efficiently burning a wide range of fuels including difficult to process municipal and industrial wastes. Inherent design features such as: 6 |