Power Plant Water Recycle

Duraflow Tubular Membranes can be used in a wide variety of applications to filter a wide range of particles beyond Industrial manufacturing. One such application that Duraflow was involved with was the installation of system to provide 100% recycling of the cooling tower blowdown at a gas-fired power plant in Southern California.

The major contaminants that the system needed to be able to filter out included Hardness (Calcium and Magnesium), Silica, Organic Compounds (Anti-scalant and Dispersants), and Total Suspended Solids. The system design includes a chemical softening and filtration through the Duraflow Tubular Membrane Filtration system followed by a Reverse Osmosis (RO) treatment system. The RO permeate (90% of feed volume) is then returned to the cooling tower, while the remaining waste, RO brine (10% of feed volume) is fed into a two-stage thermal system that evaporates the remaining water for recycling and converts the soluble salts into crystalline solids that can then be disposed of in landfills.

This particular installation uses a cross-flow configuration with 216 Duraflow DF 415 modules (10 tubes per module). The membrane tubes are each one-inch in diameter to tolerate high TSS feed concentrations with a membrane area per module of 15 square feet. The modules are actually installed on six 36-module skids with 3-4 skids in service mode at any given time while another 2-3 remain in standby mode, giving the system a certain amount of needed redundancy.

For this system, the Duraflow modules are cleaned once every 1-1.5 weeks and replaced every 5-6 years. The RO system is cleaned every 5-6 months and replaced every 4-5 years to keep the entire system running at full productive capacity.

For a complete analysis of this installation including more details about the filtration system, the chemical process used to remove the hardness and silica particles and how it is controlled, please read the full case study here.