Roy Payne

Alternative fuel reburning

Abstract Advanced reburning is a NO x control technology that couples basic reburning with the injection of nitrogen agents and promoter compounds. Pilot scale experiments were conducted in which efficiency of basic and advanced reburning processes were characterized with a wide range of reburn fuels. Test fuels included natural gas, pulverized coal, coal pond fines, biomass, refuse derived fuel, and Orimulsion. Process variables that were studied included reburn fuel type, reburn fuel heat input, reburn zone residence time, initial NO x concentration, nitrogen agent injection temperature, and promoter type and amount. Reburn fuel properties found to affect the performance most significantly include fuel nitrogen content, volatiles, and ash constituents. Basic reburning performance for the tested solid fuels was found to approach that of natural gas reburning, with over 70% NO x reduction achievable at reburn heat inputs above 20%. Advanced reburn tests were conducted in which reburning was coupled with injection of nitrogen agents and promoters. The most effective promoter compounds were found to be alkalis, most notably sodium compounds. At reburn heat input of 10%, NO x reductions in the range of 85%–95% were achieved with natural gas and biomass advanced reburning.

Application of numerical simulation and full scale testing for modeling low NOX burner emissions

Design and application of low-NOX burners and other combustion modification technologies to coal-fired boilers rely largely on the designers expertise, garnered from previous experience and engineering intuition. Use of this ‘tried-and-true’ methodology for low-NOX technologies results in some risk when these technologies are applied to conditions or boiler designs that are outside of the normal experience base. GE Energy has found that the use of advanced design tools such as computational fluid dynamics (CFD) modeling in designing low-NOX burners can ensure an effective match between the burner design and the combustion system. However, the previous design experience also indicates that model validation against test data is essential to the success of applying CFD simulation in facilitating burner design. This paper summarizes the results of a study of a low-NOX burner for coal-fired boilers. The study was focused on validating the CFD predictions on NOX emission against a single burner full scale experimental measurements. The CFD predictions along with the full scale test results were also used to evaluate design changes in the burner to ensure optimal performance for the particular application.

Application of CFD for a low-NOx burner retrofit to a coal-fired utility boiler

The design and application of low-NOx burners and other combustion modification technologies to coal-fired boilers typically relies largely on designer know-how and previous experience. There is always some risk inherent in applying NOx control technologies to new applications. This risk is offset by the use of design tools such as computational fluid dynamics (CFD) to analyse and simulate system operation. This paper presents the results of a study designed to validate the application of a combined coal/fuel oil burner to a coal-fired boiler. The modelling study includes simulation of windbox air distribution and detailed modelling of the low-NOx burner alone, and as installed on the furnace. The results of the study validate the burner design for this new application and demonstrate the utility of CFD in studying such systems.