Chilled Water Reclamation for Use as Cooling Tower Makeup.

Chilled Water Reclamation for Use as Cooling Tower Makeup.

Blue Sphere was recently challenged by a client in the cotton yarn production industry to reduce their facility water consumption.  As is typical with most textile operations, this plant regulates temperature and humidity on the production floor using air washers, cooled by a chiller and tower system.  The capacity of the system is 1300 ton or roughly 15.6 million BTU/hr.

The facilities single largest consumer of city water is the cooling tower.  The tower runs at maximum capacity over 90% of the year.  The tower runs at around eight cycles of concentration and draws approximately 35 gallons per minute (gpm) of makeup water nearly around the clock. 

The facility is located in humid, South Western Louisiana.  This means that for the bulk of the summer months, the facility air washers operate in a dehumidification mode.  This mode pulls water vapor from the plant air and imparts it into the chilled water reservoir within the air washer.  When the air washer operates in a dehumidification mode for extended periods of time, the chilled water overflows to drain.

The purpose of the reclamation project was to recycle the air washer overflow.  From a point of water quality, the air washer overflow is nearly ideal.  The water has virtually zero mineral content and no suspended solids.  Additionally, the water is chilled to approximately 50F. 

To accomplish the reuse goal, Blue Sphere installed a simple, air powered, polypropylene double diaphragm pump (AOD).  Chilled water in the air washer is preferentially drawn in by the AOD pump and supplied to the cooling tower before it can overflow into the drain.  The outlet of the plumbing in the cold water basin of the cooling tower is outfitted with a simple mechanical float valve.  The AOD pump runs constantly as it is not damaged by drawing air into its suction.  The selected AOD pump has a maximum capacity of 4gpm, but has been dialed back to approximately 2gpm.   

Our initial estimates calculate that the facility will save 20,000 – 40,000 gallons of water per month as a result of the economical project.  The temperature drop across the condenser will also be closely monitored in the coming months to determine if the low temperature of the recycled water has a positive impact on tower performance.    


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