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Show The furnace is water-cooled and simulates the geometry of B&W's single-cyclone, front-wall fued cyclone boilers. It consists of four separate water-cooled sections. The lower part of the furnace can be converted to a PC ftring scheme. The SBS facility has been operating for a total of 6 years, with the last 3 years being operated in the cyclone configuration. This cyclone facility has been proven to simulate typical full-scale cyclone units via furnace/convective pass gas temperature proflles and residence times, NOll levels, cyclone slagging potential, ash retention within the resulting slag, unburned carbon, and fly ash particle size. A summary of these comparisons is shown in Table 3. Table 3 COMPARISON OF BASELINE CONDITIONS FOR SBS FACILITY AND COMMERCIAL UNITS Typical Cyclone- SBS Fired Boilers Cyclone Temperature >3000°F >3000°F Residence Time 1 .4 sec at full load 0.7-2sec Furnace Exit Gas Temperature 2265°F 2200° - 2350°F NO. Level 900 - 1 200 ppm 600 - 1400 ppm Ash Retention 80 - 85% 60 - 80% Unburned Carbon <1% in ash 1 - 20% Ash Particle Size (MMD; 8ahco) 6 - 8 microns 6 - 11 microns The inside surface of the furnace is insulated to yield a FEGT of 2265°F at the design heat input rate of 6- million Btu/hr. A water-cooled tube bank simulates the flue gas time/temperature history inherent in full-scale cyclone convective passes. The tube bank consists of four separate sections for simulating a secondary superheater, reheater, primary superheater, and economizer. Each section consists of a water-cooled jacket and tubes to quench the flue gases. All four sections are connected to a common atmospheric drum. This use of convective tubes to cool the gas, in conjunction with the cyclone furnace, makes this a unique facility among pilot-scale combustors. Two reburning burners were installed on the SBS furnace rear wall at an elevation above the cyclone burner/ barrel. The facility is capable of frring natural gas, oil, or coal at the reburning burner region. The multi-fuel reburning burners are designed to accommodate the required velocities for furnace penetration and also to allow for enough flexibility for varying mixing characteristics. Each burner consists of essentially two zones with the outer zone housing a set of spin vanes while the inner wne contains the reburning fuel injector. Air and flue gas recirculation (FGR) can be introduced through the outer zone. The natural gas/oil burners also have the capability to bias the air/FGR flow between the inner/outer zones. Overfue air ports are available on both the front and rear walls of the SBS at three elevations, with each elevation containing two ports. Locating the OF A ports at different elevations assists in assessing the effects of residence time on fuel burnout and NOll reduction. The SBS furnace and convection pass sections are equipped with numerous observation ports at different elevations to allow for complete evaluation of the process under investigation. In-furnace probing is performed at the port locations in order to determine temperatures and gas/solids composition. 7 |