机载相位多普勒粒子干涉仪用于云微观物理特性测量

High-level Nitrogen oxides (NOx) released to the atmosphere cause health and environmental hazards. Conventional power plants are required to have NOx emission control systems to abide by local environmental regulations. Com-mon post-combustion techniques include selective non-catalytic reduction (SNCR) or selective catalytic reduction (SCR) techniques. SNCR is a proven technology that can be implemented virtually without affecting existing indus-trial operations with low capital cost. SNCR is a method involving either aqueous ammonia or urea as the reagent injected into flue gas in the boiler/furnace within specific temperature range. This method commonly reduces the emission of NOx by 30-50%. However, high reductions can be achieved by system optimization. Placement within the proper temperature window, distribution within the cross section and residence time of reagent significantly in-fluence performance of an SNCR system. Therefore, spray lance and nozzle design is crucial for assurance of oper-ating efficiency and ammonia utilization. In this paper, an SNCR system in a circulating fluidized bed (CFB) boiler was studied with using Computational Fluid Dynamics (CFD) simulations, as it relates to spray technology. The simulation solves Navier-Stokes equa-tions with heat and mass transfer using ANSYS Fluent SNCR model with Lagrangian multiphase models and spe-cies transport model. CFD was used to diagnose the gas phase behavior and thermal distribution, to determine opti-mal spray placement and maximum penetration. The focus of this work was the parameters of the injection, which were determined based on test data acquired through in-house laboratory equipment. Temperature profile, pollutant reduction, ammonia slippage and wall impingement were used from the CFD results to assist determining the best spray design to achieve the greatest efficiency.