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Conductivity of DM water in storage tank is increasing

December 30, 2009

Dear All,

We are operating Gas Based Combined Cycle power plant. We have 2 streams of DM Plant with Solid Contact Clarifier as a Pre Treatment of raw water.

We are producing DM Water at 30 M3/Hr. flow with < 0.1 microsiemens/cm conductivity. This DM water is stored in 500 M3 air tight storage tank. Although this storage tank is provided with KOH Breather,the Conductivity of this DM water reached to 0.65 microsiemens/cm.

What action is required to bring down the Conductivity of DM water in Storage tank outlet.

Dharmendra Mahida
plant operator - Gujarat, India

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December 30, 2009

I see two choices: the most common is CO2 dissolving in the water in spite of your KOH breather and two, you are dissolving leach able material into your DI water. You have fairly pure water and it will leach out materials from several types of tank material.

A test for #1 would be to put a nitrogen flow into the tank for a week or so to see what effect that it has of keeping out any oxygen/CO2. A very low flow in static conditions should work fine. It is not a large cost to verify/eliminate it as a problem.

One solution is to plan ahead well enough that you can eliminate one or more storage tanks and have your DI stored for only a day or two--hello just in time work.

James Watts
- Navarre, Florida

Provide air tight water jacket lids to prevent direct air contact. Put air escape vent at the center of opening with non return valve .

Dattatray Dangat
- Mmbai, Maharashtra, India
January 1, 2010