OCR Text |
Show reburn fuel, carrier gas recirculation, and burnout air, as well as injection elevation in the furnace, were specified from the process flow calculations described previously. Candidate reburn fuel and burnout air injector configurations were identified based on previous experience. These configurations were then screened by calculating expected jet trajectories for each configuration's reburn fuel and burnout air nozzle arrangement. It was assumed that all the reburn fuel and burnout air injectors would be located on the boiler front and rear walls. The boiler side walls were not considered for potential injector locations because of equipment interferences on the host unit. A 1/16-scale, geometrically similar, isothermal (cold flow), clear plastic flow model of the Ladyzhin boiler w as then fabricated. This model, shown in Figure 3, simulated the boiler from the furnace bottom to the inlet of the economizer section. The first series of tests performed in the cold flow model was an evaluation of the Ladyzhin furnace's aerodynamics with the model simulating normal baseline (non-reburn) operation. A qualitative evaluation of the flow field was performed, using smoke to trace jet penetration and mixing; limited quantitative tests were also performed to establish three-dimensional furnace gas velocity profiles under baseline conditions. Reburn system configurations were tested in two phases. Phase 1 evaluated the performance of candidate reburn fuel injection hardware arrangements without a burnout air system in operation. Phase 2 evaluated the performance of candidate burnout air injection hardware arrangements with the best-performing reburn fuel system from the Phase 1 efforts. Nozzle free areas and mass flow rates were the key variables investigated in a comprehensive series of tests in the physical flow model. Furnace Thermal Performance The objective of this phase of the preliminary design study was to investigate the potential impact of retrofitting a reburn N O x reduction system on furnace thermal performance for the Ladyzhin Power Station host boiler. Objectives were to determine if changes would occur in furnace horizontal exit gas temperature, Figure 3: Ladyzhin Flow Model 6 11-12 |