AquaSweepTM Separator Inertial Separation – An Alternative to Screening of Aquatic Life and Closed Loop Cooling Tower Retrofit to Meet 316(b) Requirements

The protection of aquatic life from impingement and entrainment (IM&E) by power plant cooling water intake structures (CWIS) has been a topic of study and implementation for several decades. A wide array of screening techniques have been employed with varying degrees of success. While IM&E reductions approaching 90% for “large” aquatic organisms such as adult fish have been successfully demonstrated by a number of technologies – IM&E reductions for small aquatic organism such as eggs and larvae in an economical and maintainable fashion has been more elusive.

Section 316(b) final draft regulation by the EPA is schedule for publication in March 2011 with enactment in July 2012. This regulation is anticipated to have a significant impact on the power generation industry by requiring reductions in IM&E of once through cooling (OTC) intakes to levels that have only been demonstrated by closed cycle cooling towers (CCCT). The cost of converting existing U.S. power plants which use OTC to CCCT has been estimated at more than $100 billion.

The AquaSweep Separator is based on the principle of inertial separation – not screening – to separate small aquatic life from the CWIS. By definition, screening requires the largest “hole” in the screen to be smaller than the smallest aquatic organism being excluded. Inertial separation relies on the inertia of the aquatic life to guide it away from the water flow entering the CWIS. By employing inertia, the largest “hole” in the AquaSweep Separator can be larger than the smallest aquatic life being excluded. A direct benefit is a smaller cross sectional area of active separator face when compared to the active screen face required for other technologies. In addition to AquaSweep’s benefits of a smaller footprint, its larger “holes” are less likely to clog with debris and are easier to clean given their linear geometry.

This presentation will show the footprint, conversion cost, and maintenance benefits of the AquaSweep separator when compared with screening technologies and CCCT conversion. Computational fluid dynamics modeling by CH2M Hill and aquatic life studies performed by Alden Research Laboratory results will also be presented.