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Show 2. RESEARCH FURNACES 2.1 Air Liquide's Research Facilities in France Air Liquide committed in 1996 to design and manufacture a new 2.0 M W test furnace capable of operating at up to 1600°C. This furnace, built and commissioned in 1997, was conceived with the objectives of integrating advanced classical and optical diagnostics into a practical, efficient testing facility. The maximum operating temperature of 1600°C allows testing oxy-burners in a thermal environment representative of many high-temperature industrial furnaces. The combustion chamber is 6.0 m long, and has a rectangular cross-section of 1.5 by 2.0 m (Figure 1). These internal dimensions are large enough to minimize flame confinement effects and permit investigating the interaction between the flame aerodynamics and the furnace recirculation zones. The furnace can operate with natural gas, propane, light and heavy fuel oils from 100 k W to 2.0 M W (0.34 to 6.8 MMBtu/h). using oxygen-enriched air or pure oxygen as oxidant. The 300 m m thick low thermal inertia bricks which cover the walls and roof are made of alumina-based cast fibers. Heat losses through fiber bricks at 1600°C do not exceed 50 K W , which corresponds to a heat flux of 0.8 kW/m:. Thermal equilibrium is obtained after about 7 to 9 hours after start-up, following a heat up ramp not exceeding 150°C/h above 1100°C. Furnace roof axial temperature profile is measured by 11 type S thermocouples. The furnace floor consists of 13 water-cooled sections, providing detailed characterization of the heat extraction profile. Heat extraction and furnace outlet temperature can be varied over a large range by partially insulating the sides of the water-cooled load, and/or by covering part of the load with a radiative screen consisting of Silicon Carbide panels. Probe and optical access is provided on one side by a 150 m m high slot running over the whole furnace length. O n the opposite side are located 13 ports typically used for optical measurements, visual observations or mounting of video recording equipment. Further, three ports are located above and on both sides of the furnace outlet, also for flame observation and video recording. Finally, a 150*150 m m quartz window located in the furnace roof above the near burner zone is used for imaging techniques such as pulsed laser sheet visualization and O H Imaging. A n electric damper in the chimney duct allows regulating the furnace pressure and av oiding air leakage into the furnace. A furnace overpressure of 1.6 m m H2 0 is sufficient to obtain a (CO:+ O;) concentration above 9 5 % (dry flue gas), the remainder corresponding to nitrogen introduced with the natural gas. Exact natural gas composition is frequently monitored by a micro gas chromatograph (MTI model Q30L). Turbine meters on the natural gas and oxygen lines provide a flow rate accuracy of ± 0.2% of the actual flow rate. Peripheral to the furnace, an electronic monitoring and regulation system interfaced to computer controls and continuously archives over 200 measured parameters. This system provides real-time information on parameters such as burner inputs, flue gas composition and temperature, furnace axial heat extraction and thermal profile, along with mass and heat balance. The furnace control system also includes safety systems that prevent unsafe operation and. if required, automatically shutdown the burner fuel/oxygen supply. With this control system, firing rate/temperature ramps and furnace pressure can be programmed and automatically regulated. These features allow unattended operation of the furnace at night and over the weekend, and guarantee operation of the furnace at thermal equilibrium over entire working days. Figure 2 displays an example of furnace input and output parameters recorded over a period of four hours. It can be seen that the burner flow inputs are controlled with high accuracy and that the flue gas composition is stable. Oxygen and C O : concentration in the dry flue gas are controlled within ±0.2%. while the repeatability of the heat extraction and thermocouple temperature is within ±5 k W and ±5°C. The ability to accurately control and measure furnace and burner parameters is key to efficient acquisition of reliable, repeatable data. A 3-D traversing system was designed for in-flame probe measurements in the horizontal and vertical planes crossing the axis. Translation in the vertical plane is accomplished by moving the probe carrier along a curved rail that provides a probe rotation around a non-material axis. The three stepper motors can be operated in Cartesian or cylindrical coordinates. Positioning accuracy was verified to be 1 m m or better on all x.y.z axes. Other test facilities include two cylindrical furnaces with internal dimensions of 0 0.5*1.9 m. These alumina bricks lined furnaces can operated at up to 150 k W and 1600°C. One of them is also equipped with a flue gas cleaning system allowing burning waste simulating liquid and gaseous mixtures. Details of its characteristics can be found in [4]. Last, an open air facility is also available for testing burners at up to 6.0 M W . If required, the flame can be confined by a fiber lined cylindrical section of 01.20 * 3.84 m. 2.2 Air Liquide's North American Research Facilities The Countryside facilities consist of two main furnaces for studying oxy-fuel combustion. For industrial scale experiments a pilot furnace with dimensions 1.0*1.0*4.0 m shown in Figure 3 is used with a 730 k W (2.5 MMBtu/hr) 2 |