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Show these sprays onto tube walls in order to avoid corrosion and fouling which can lead to structural failure. Furthermore, improper spray patterns result in less than adequate chemical distributions and lessen the opportunity for effective flue gas treatment. For these reasons, the spray model serves a valuable purpose in predicting acceptable spray characteristics for a given project. The spray model was derived from an early version of a particulate trajectory program called GENTRA (Cham).lS) GENTRA was derived from the PSI-Cell modell1°) for droplet evaporation and motion, and is convenient for iterative CFD solutions of steady state processes. The PSI-Cell method uses the gas properties from the fluid dynamics calculations to predict droplet trajectories and evaporation rates from mass, momentum, and energy balances. The momentum, heat, and mass changes of the droplets are then included as source terms for the next iteration of the fluid dynamics calculations, hence after enough iterations both the fluid properties. and the droplet trajectories converge to a steady solution. A number of changes were made to the code to make it more efficient and applicable to NOxOUT applications. Sprays were treated as a series of individual droplets having different initial velocities and droplet sizes emanating from a central point. Correlations between droplet trajectory angle and the size or mass flow distribution have been included, and the droplet frequency was determined from the droplet size and mass flow rate at each angle. The model has been further modified to predict multicomponent droplet behavior. The equations for the force, mass, and energy balances were supplemented with flash calculations, providing the instantaneous velocity, droplet size, temperature, and chemical composition over the lifetime of the droplet. The momentum, mass, and energy contributions of atomizing fluid have also been included. The correlations for droplet size, spray angle, mass flow and droplet size distributions, and droplet velocities were found from laboratory measurements using laser light scattering and Doppler techniques. Characteristics for many types of nozzles under various operating conditions have been determined and were used to prescribe parameters for the CFD model calculations. Examples of Model Results The conditions encountered in application of the NOxOUT Process have varied widely. Examples have been selected to demonstrate NOxOUT model results for several different types of process units. In practice, the data are displayed on a high resolution color monitor, and color hard-copies of the display are generated. For this paper, the data are displayed in black-and-white, which limits the types of figures that are effective for visualization. I t was decided for clarity to suppress from the images any text, including descriptions of the magnitudes of velocities, temperatures, or chemical compositions. Data are presented in cross sections through the geometry, with scalar properties such as -6- |