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Show Table 2 Coal Design 825°F Predicted RDF Design Perf. 700°F Actual RDF Performance Superheater Steam Outlet Temp. Superheater Outlet Steam Flow Superheater Outlet Steam Press. Economizer Inlet Feedwater Temp. Economizer Outlet Temp. 125,0001b/hr 105,9001b/hr 720°F 109,0001b/ hr 604 psig 340°F Furnace Exit Gas Temp. Boiler Outlet Gas Temp. Economizer Exit Gas Temp. 625 psig 330°F 1820°F 417°F 625 psig 330°F 359°F 378°F 1567°F 1480°F 729°F 660°F 648°F 590°F Air Heater Exit Gas Temp. Undergrate Air Temp. Not Applicable 450°F 420°F 353°F 315°F Boiler Efficiency 80.15% 69% 70% 13890 sq. ft. 3945 sq. ft. 6139 sq. ft. 9180 sq. ft. 1730 sq. ft. 8250 cu. ft. 12086 cu. ft. Boiler Bank Heating Surface Superheater Heating Surface Economizer Heating Surface Effective Furnace Volume Furnace Liberation Rate Grate Heat Release 23600 Btu/hr Ift3 13652 Btu/hr/ft3 638954 Btu/hr I ft2 539216 Btu/hr/ft2 Excess Air 30% 50% 65% Economizer Gas Flow Combustion Air Flow 229000lb/hr 2344001b/hr MW Overfire Air Static U ndergrate Delta P 18800lb/hr Data is from the Red Wing Unit 2. Wilmarth data is comparable. Overfire air / undergrate ratios of 51149 typical. SUMMARY The repowering of the Red Wing and wilmarth power plants to fire refuse-derived fuel demonstrates how NSP, working closely with county agencies and selected vendors, was able to alleviate an increasing problem of solid waste disposal. The conversion project is on time, within budget, and presently has all four steam generators on line, firing refuse. The extensive modifications to the steam generators will permit NSP to use the RDF it processes from the Ramsey and Washington Counties' trash to generate power for years to come. The steam generator modifications have resulted in applying conservatively designed upgrades to insure the high reliability necessary for NSP to meet the contracted commitments of trash acceptance. 187600lb/hr2 REFERENCES 9.9 23" H20 1.3" H20 1. Skinner, M.F., and Bloomer, T.M., "Red Wing and Hilmarth Steam Plants RDF Conversion" Joint Power Generation Conference, Portland, Or., 1986. 2. Kreidler, L. and Gibbs, D., "From Hamilton to Palm Beach: The Evolution of Dedicated RDF Plants", presented to Processed Fuels & Materials Recovery from Municipal Solid Waste Symposium; sponsored by Resource Recovery Report and Gershman, Brickner & Bratton, Inc., Washington D.C., 1986. Available from B&W as BR-1294. |