Heat Recovery Steam Generator (HRSG) Flow Control Design
A Heat Recovery Steam Generator (HRSG) had suspected flow deficiencies which was causing suboptimal performance of the unit. Alden was contacted to use CFD to conduct an evaluation of the unit and design flow controls to improve its steam generation.
To complete this evaluation, Alden developed a baseline CFD model of the HRSG from the turbine outlet to the tube bank inlet to understand how the flow develops in this section. An area of recirculation and the reasons it developed were identified. A set of flow controls was designed to address the recirculating gas. Alden worked with the client to ensure that the flow controls were both effective and practical to construct and install into the existing system.
Results
Using the drawings provided, the oil & gas plant constructed and implemented the flow controls designed by Alden. Subsequently, the plant saw a 17% improvement in steam generation when the unit was tested with the new flow controls
Project Highlights
- CFD model identified flow inefficiency
- Flow controls were iteratively designed with input from the clients
- Steam generation increased 17% after implementation of the flow controls
Capability
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.