Computational Fluid Dynamics Based Investigation of Sensitivity of Furnace Operational Conditions to Burner Flow Controls
This is the Final Technical Report for DOE Cooperative Agreement No: DE-FC26-02NT41580. The goal of this project was to systematically assess the sensitivity of furnace operational conditions to burner air and fuel flows in coal fired utility boilers. The focus of this project was to quantify the potential impacts of ''fine level'' controls rather than that of ''coarse level'' controls (i.e. combustion tuning). Although it is well accepted that combustion tuning will generally improve efficiency and emissions of an ''out of tune'' boiler, it is not as well understood what benefits can be derived through active multiburner measurement and control systems in boiler that has coarse level controls. The approach used here was to utilize existing baseline furnace models that have been constructed using Reaction Engineering International's (REI) computational fluid dynamics (CFD) software. Using CFD analyses provides the ability to carry out a carefully controlled virtual experiment to characterize the sensitivity of NOx emissions, unburned carbon (UBC), furnace exit CO (FECO), furnace exit temperature (FEGT), and waterwall deposition to burner air and fuel flow rates. The Electric Power Research Institute (EPRI) provided co-funding for this program, and instrument and controls experts from EPRI's Instrument and Controls (I&C) Center have been active participants in this project. CFD simulations were completed for five coal fired boilers as planned: (1) 150 MW wall fired, (2) 500 MW opposed wall fired, (3) 600 MW T-Fired, (4) 330 MW cyclone-fired, and (5) 200 MW T-Fired Twin Furnace. In all cases, the unit selections were made in order to represent units that were descriptive of the utility industry as a whole. For each unit, between 25 and 44 furnace simulations were completed in order to evaluate impacts of burner to burner variations in: (1) coal and primary air flow rate, and (2) secondary air flow rate. The parametric matrices of cases that were completed were defined in order to accommodate sensitivity analyses of the results. The sensitivity analyses provide a strategy for quantifying the rate of change of NOx or unburned carbon in the fly ash to a rate of change in secondary air or fuel or stoichiometric ratio for individual burners or groups of burners in order to assess the value associated with individual burner flow control. In addition, the sensitivity coefficients that were produced provide a basis for quantifying the differences in sensitivities for the different boiler types. In a ranking of the sensitivity of NOx emissions to variations in secondary air flow between the burners at a fixed lower furnace stoichiometric ratio in order of least sensitive to most sensitive, the results were: (1) 600 MW T-Fired Unit; (2) 500 MW Opposed Wall-Fired Unit; (3) 150 MW Wall-Fired Unit; (4) 100 MW T-Fired Unit; and (5) 330 MW Cyclone-Fired Unit.
- Research Organization:
- Reaction Engineering International, Midvale, UT (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- FC26-02NT41580
- OSTI ID:
- 859091
- Country of Publication:
- United States
- Language:
- English
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