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Texas Plant Revamps its RO Pre-treatment with Pall Aria™ Microfiltration System |
Introduction
Until 2002, a supercritical plant in Texas equipped with three 750MW Westinghouse steam turbines and CE tangential supercritical boilers, was using a clarifier for pre-treatment of cellulose acetate RO membranes to provide condensate make-up.
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The Problem
The large clarifier exhibited signs of corrosion due to the acidic treatment of the water in the process. In addition, the quality of the water was deteriorating, and conductivity increased due to ferric sulfate and caustic addition. The plant also reported difficulty in stabilizing water chemistry, averaging 2 or 3 days to stabilize the system after a change in demand or influent chemistry.
The plant was experiencing an increase in the cost of chemicals (up to $50,000/year) to try to catch up with a failing and deteriorating system. Initial estimate of repair and upgrade to the clarifier system was $300,000.
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The Solution
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| Pall Aria™ AP-4 microfiltration system treats 300 gpm (total output for 2 AP-4 is 600 gpm to the plant) |
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The Benefits
- A consistent water quality of 0.04 NTU out of the Pall Aria™ system, for a wide range of upstream water conditions
- At least 6 months of operation between CIP (clean in place)
- The ability to change flow on demand from the PLC without major adjustment
- Reduction of the maintenance required for the pretreatment process by a factor of 6
- Extension of the service life of the filter element upstream of RO, from 3 days to longer than 6 months.
- A significant reduction (more than 60%) in space needed for water treatment
- Return on Investment of six months
- Man hours reduced by 100,000 hours
- Chemical cost reduction of $50,000 per year
- Savings of $250,000 per year, capital previously spent on filter media for clarifiers
- 3 years with zero hours downtime
- Savings of $2000 per month, capital previously spent on polymer addition
- First year savings of approximately $500,000
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