Case Study: Filter reduces flood-induced suspended solids in New Orleans heat exchangers

Oct. 17, 2014

The Project

Enwave USA (formerly Entergy Thermal), located in New Orleans, La., completed the design-­build of a new District Energy Center in the city to provide services to the New Orleans Regional Medical Center (NORMC) and other clients. The facility provides more than 33,000 tons of chilled water and air conditioning to more than 12 million square feet of commercial property that encompasses 15 square city blocks.

Post Katrina

In 2009, Hurricane Katrina flooded the entire city, which led to elevated total suspended solids (TSS) levels in all its cooling water systems. This in­crease in TSS caused fouling of the heat exchangers, resulting in a significant loss in efficiency and increase in maintenance costs.

Jeff Davis, director Plant Operations for Enwave USA, attended the IDEA Expo in Wash­ington D.C., looking for solutions to improve his bulk chilled water quality in the aftermath of considerable damage caused by flooding. As such, he visited the Sonitec-­Vortisand booth and met with Regional Manager Keith Karl.

Jeff Davis, Director Plant Operations for Enwave USA

The Challenge

David discussed the challenges they were having with poor water quality negatively impacting the performance of their large thermal chilled water supply. They had tried traditional media filters and did not succeed in reducing the level of TSS.

It was determined the best solution to clean up this large volume chilled water loop, while keeping within a tight bud­get, would require a 300-gallons-per-minute (GPM) Vortisand® cross-flow microsand filter that provided submicron filtration and high-quality water.

The Vortisand system replaced a traditional sand filter that claimed 5 micron capability. A standard laser particle distribution analysis illustrated that 80 percent of the TSS were less than 5 micron in size.

The new Vortisand unit was installed in early 2010 and after several months of operation proved to be a wise investment for them. Typically, 99-percent removal of particles smaller than 5 microns is achieved after 90 days. Proof that a quality cross-­flow microsand submicron filtration system coupled with a comprehensive chemical treatment program was the key to reducing TSS levels.

The Results

During a recent site visit in April 2014, Davis stated that he has never seen the chilled water this clean since the start­up of the facility in 2000. The TSS issues that previously plagued the entire system never returned. Previously, their 15 heat exchangers had to be cleaned sev­eral times per year due to the increased biofilm caused by the suspended solids.

"These heat exchangers have not had to be cleaned since the Vortisand was installed in 2010," said Davis. Maintaining their design efficiency has improved the bottom line every year with a return on investment of less than 12 months.

See also:

"Case Study: Centrifugal filtration boosts energy efficiency, savings for Canada deep water cooling system"

"Case Study: DC five-star hotel overcomes cooling tower sludge issues with advanced sand filter"

About Sonitec

Sonitec was founded in 1986 offering an innovative technology: the Vortisand. Behind each Vortisand system you will find a dedicated company with more than 2,500 installations worldwide. Certain innovations have allowed the company to become a specialist in filtration for pharmaceutical, petroleum refining, biotechnology, pulp & paper, automotive, and general HVAC sectors. Recent breakthrough installations include Vortisand filters on cooling systems of major projects operated by major market leaders such as eBay, Conoco-Philips, GM and more. For more information, visit www.sonitec.com/en/home.html.

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