Wet Flue Gas Desulphurization System Optimization
A streamlined modeling approach reduced both cost and time to achieve an optimized design solution.
Williams Station Unit 1 is a 610 MW coal fired station owned by South Carolina Electric & Gas (SCE&G). The plant installed a new wet flue gas desulphurization (WFGD) system, which removes SO2 entrained in the flue gas stream. The approach of the physical flow model study was to minimize the potential for liquid pullback into the absorber inlet ducts by improving the gas flow distributions into the absorber. A parallel CFD model study was performed to optimize the spray nozzle locations and spray types to reduce high gas velocity zones and create a uniform even spray coverage across the absorber vessel to optimize SO2 removal.
Computational fluid dynamic (CFD) and scaled physical models of the planned WFGD system used velocity inlet profiles based on field data to provide better accuracy of the simulations. Modifications to the inlet ductwork and within the WFGD were made to improve the gas flow and SO2 removal efficiency. The CFD model was also used to design and optimize the spray nozzle grid and wall rings while the physical model minimized the potential for liquid pullback into the inlet ducting with designs to the inlet awning. The results of the study provided flow controls and a spray nozzle injection grid design to minimize liquid pullback while providing uniform spray coverage, which is necessary to optimize SO2 removal.
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Civil InfrastructureServices
Gas Flow Modeling and DesignRelated Projects
An existing roof vent arrangement was allowing rainwater to enter the Pot Room. Alden supported efforts to develop a roof vent geometry to eliminate the intrusion of rain water. The purpose of the CFD study was to ensure that the roof vent modification did not increase pot room temperature levels beyond specified limits for workers in the plant.
To evaluate the existing and proposed Pot Room arrangements, thermal and fluid flow profiles in the immediate vicinity of the pots were determined based on air flows through the plant floor and wall mounted vents. The detailed CFD model was developed from plant drawings to include all major basement, pot room and roof venting geometries. The surrounding ambient environment was included with quiescent atmospheric conditions and average ambient temperature. Thermal losses form the pots to the pot room air and from the pot room to the environment were included in the analysis. The results of the CFD modeling showed that the proposed modification to the roof venting arrangement was acceptable and would not increase the temperature in the worker-occupied spaces by more than 2 degrees F.
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Civil Infrastructure
Smelter Pot Room Roof Ventilation System
Read how a CFD study ensured that a roof vent modification did not increase pot room temperature levels beyond safe levels
Plant McDonough, owned and operated by Southern Company, has experienced excessive siltation at the makeup water intake. The intake uses cylindrical wedgewire screening within an intake originally designed for much larger, once-through cooling water flows. Flow modeling was performed to provide a viable passive solution to reducing the sediment accumulation at the intake. To model the geometric details of the system accurately, a field survey was performed prior to the flow modeling efforts. The flow study included both CFD modeling and scale physical modeling.
For this investigation, Alden developed a 1:20 scale live bed physical model. This model was extremely well tuned to reproduce the behavior of bed load sediment. Even with the very fine crushed walnut shell particles, however, it was challenging to reproduce the behavior of suspended load. The use of a high fidelity CFD model, therefore, proved extremely useful for this project, in that suspended load is generally very accurately tracked with CFD models, which are not well validated for bed load simulation. By using the two together, the two extremes of sediment transport are captured, and developing a solution that covers this range has a high likelihood of success.
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Civil Infrastructure | Hydrology Hydraulics and Fluids
Plant McDonough Intake Modification
CFD and physical model study to assist in the evaluation of a solution to reduce the sediment accumulation.