Water Fit for Use Avoiding the Unintended Consequences of Good Intentions Ronald Tebbetts Industrial Technical Consultant, Global rtebbetts@nalco.com (225) 276-7769
Water Flow Diagram Steam Loss Venting Cooling/Scrubber Evaporation Purchased Water Rain Surface Water Plant Processes Water in Product Well Water in Crude WWT Direct Discharge
So what is the usual response? Purchased Water Surface Water Plant Processes Well Improve the supply Find a new source Drill a well Install another pump Municipal Waste Water» El Paso Reclaim Water» Title 22 Water in California
Water Conservation Efforts High Recycle Cost Reuse Reduce Low Low Effort/Risk High
Where is the Water being used?
Step One: Reduce your use aka: The Low Hanging Fruit Increase Cycles Cooling and Steam Systems Stop uncontrolled blowdown Reduce tower drift Regulate or automate the blowdown Stabilize make-up preparation Make sure the tower is running efficiently
Improve Cycles of Concentration 700 Impact of Cycles : Water Savings 600 500 Blowdown (GPM) 400 300 200 100 0 2 3 4 5 6 7 8 9 10 Cycles of Concentration Blowdown flow based on 50,000 gpm recirculation rate and 15 o F Delta T
Improve Cycles of Concentration Impact of Cycles : Water Savings vs. Risk Blowdown (GPM) 700 600 500 400 300 200 100 200 180 160 140 120 100 80 60 40 20 CaCO3 SI 0 2 3 4 5 6 7 8 9 10 Cycles of Concentration 0 Blowdown flow based on 50,000 gpm recirculation rate and 15 o F Delta T
Reduce your use Optimize Filter/Ion Exchange Processes Condensate Recovery Fix steam leaks Steam Trap maintenance Vent Condensers
Reduce your use Consider Dry Cooling or hybrid towers (Adiabatic Towers)
Step Two: Reuse what you have. Hydraulic Model
If water were pure, we could use it over and over and over.
The Problem Ions Scaling Ions Calcium Magnesium Silica Deposition Concerns Iron Manganese Aluminum Corrosive Ions Sulfates Chlorides Alkalinity (HCO3, CO3)
So Optimizing Water Use is a Salt inventory management challenge
AND Chemistry is the primary driver
You need an Ionic Model
Reuse what you got Filter/Demineralizer Backwash Usually Clarified Raw Water Will contain some turbidity Collect Condensates being sewered SWS or OH Water for Desalter Wash Water May contain hydrocarbons/ammonia that could affect Desalter performance
Problems with Reuse Usable water in wrong place Individual sources too dispersed and small No storage capacity May contain ions and other contaminants that are not compatible with receiving process.
Step Three: Recycle Waste Streams Steam Loss Venting Cooling/Scrubber Evaporation Purchased Water Rain Surface Water Plant Processes Water in Product Well Water in Crude WWT Direct Discharge
Cold Lime Softening RO Treatment Ultrafiltration Thermal Desalination Plume abatement Recycle Equipment (SPX Air2Air Water Recovery System)
Zero Liquid Discharge Falling Film Evap with Crystallizer Cold Lime Softener
Words of Caution Recycling concentrates the waste Understand mineral solubility Understand effects of corrosive ions Understand how it will affect system equilibrium
Words of Caution Know the WWT Permit Requirements - May have minimum flow requirements - Waste may become toxic Lower flow Higher Dissolved Solids loading - May reduce the food supply to WWT
Get Your Water Treatment Professional Involved Early in the Process
Thank you!