Centrifuge Upgrade – Hydraulic or VFD?
Pinellas County Utilities South Cross Bayou Water Reclamation FacilitySt. Petersburg, Florida
The dewatering and thickening centrifuges located at the South Cross Bayou Water Reclamation Facility (SCBWRF) have been inefficient for many years. The critical source of problems is the DC drive associated with the units. During any type of incoming power problem such as a “power blink” the machines require an entire shut down and restart. This not only costs production time but it is also difficult to adequately clean the machine during the shut down. The focus of this paper is to describe the steps taken by Pinellas County to review its options in the pursuit of having machines that are more efficient to maintain and operate. The goals of this presentation are to demonstrate the steps that PCU chose to retrofit the existing system and improve production, efficiency, operation and maintenance of the plant in general. The main source of payback for the project was realized in the reduced operation and maintenance required for the machines. The total combined PLC related repair costs over a two year period prior to the centrifuge upgrade averaged to nearly $85,000 between three technicians. The reduction in Operations labor due to PLC failures over the period of one year was approximately $55,000. The technicians were spending nearly 4 hours per 24 hour shift resolving PLC issues with the controllers. The largest savings was the ability to remove an operator from all three shifts, resulting in a savings of over $235,000 per year. This move allowed the Operations to move Operators back into the plant to fill needed positions. The overall savings of $375,000 will realize a 2.7 year return on investment based on the final cost of $1,012,043.51 which includes all change orders due to equipment condition repairs that were needed prior to the hydraulic upgrade. Source: WEFTEC 2009 Proceedings
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Posted: August 27th, 2010 | Filed under: Waste Water Treatment | Tags: Cost Savings, Improved Operation and Maintenance, Improved Plant Efficiency, Improved Production | No Comments »
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