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pH Adjustment of Power Plant Cooling Water with Flue Gas/ Fly Ash

Sandia National Laboratories

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Market Sheet
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Technology Marketing Summary

Increased recycling of power plant cooling water calls for low-cost means of preventing the formation of calcium carbonate and silicate scale.  Hardness (Ca and Mg) and silica are two of the primary water components that must be selectively precipitated or maintained in solution for intensive water recycling to be achieved.  Sandia researchers propose that available on-site flue gas and fly ash could be used to control the pH of cooling water to prevent scale formation and achieve greater recycling. 


This pH adjustment is a simple, inexpensive way to both prevent scale formation and to selectively precipitate problematic scale-forming solids.  The discovery represents a cost-effective way to utilize materials indigenous to fossil fuel burning power platns to control mineral precipitation is cooling water. 

Flue has, which is 10% CO2, could be diverted into a plant's cooling water tower, or sidestream nanofiltration feedwater, to lower the pH and inhibit scale formation while fly ask could be used to raise pH to achieve lime softening.  The same pH adjustment approaches might be applied to reduce the impact of silica scaling. 

  • Less water usage
  • Water reuse
Applications and Industries
  • Electric Utility
  • Water Supply
  • Sewage Treatment
Patents and Patent Applications
ID Number
Title and Abstract
Primary Lab
Patent 9,140,145
PH adjustment of power plant cooling water with flue gas/fly ash
A system including a vessel including a heat source and a flue; a turbine; a condenser; a fluid conduit circuit disposed between the vessel, the turbine and the condenser; and a diverter coupled to the flue to direct a portion of an exhaust from the flue to contact with a cooling medium for the condenser water. A method including diverting a portion of exhaust from a flue of a vessel; modifying the pH of a cooling medium for a condenser with the portion of exhaust; and condensing heated fluid from the vessel with the pH modified cooling medium.
Sandia National Laboratories 09/22/2015
Technology Status
Technology IDDevelopment StageAvailabilityPublishedLast Updated
US Patent Pending SD# 11372Proposed - Sandia estimates the technology readiness level at a 4. Key elements have been demonstrated in a laboratory environment. Available09/28/201110/28/2016

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