A Fresh Look at Recycle Pumping Using Optimized Hydraulics, CFD and Physical Modeling

The HRSD Virginia Initiative Plant (VIP) has had operational and maintenance issues with the Nitrate Recycle (NRCY) and Anoxic Recycle (ARCY) systems for years with the NRCY pumps suffering severe impeller wear and both systems reliant on a siphon system downstream of the pumps that frequently becomes air-bound, requiring servicing. To address these concerns, HDR modified the NRCY and ARCY systems to eliminate the siphon conditions and provide Hydraulic Institute compliant intake hydraulics at both pumps. The existing submersible pumps were replaced with vertical turbine pumps that had their intakes physically modeled to evaluate the presence of flow disturbances around the pumps. Specialized fillets and intake columns were designed to reduce turbulent flow and installed with the pumps as part of the Nutrient Reduction Improvements (NRI) project at the plant. Following the project, the pumps have been operating reliably with minimal maintenance.