The Problem

The Solution

Results Achieved

The Problem

Analysis of Deposit

The Solution

Observation

On July 11, 1991 during a conversation with employees at a southern steel mill, it was revealed that the tubes in their Power House condensers were being brushed. The comment seemed unusual because they had just mechanically cleaned the condensers 2 to 3 weeks earlier.

Investigation proved the condenser fouling was a combination of mud and biological debris. The biological mass was analyzed as predominantly pseudomonas organisms.

The facility should have been producing 30 Megawatts of electricity but the best they could obtain was 18 Megawatts. The 18 Megawatts were being generated at steam flows usually required to achieve the 30 MW production. The facility could not get the required power generation regardless of steam flow so the units had to be pulled off-line and mechanically cleaned.

When ASI initially spoke with the Power House Superintendent about treating the system, he stated that he had to be careful about costs. He knew that treating the system was going to cost him money--and he did not believe he would save money in the long run. In fact, at $35.00 per Megawatt, he was losing $10,080.00 per day because he could only produce 18 Megawatts (versus the 30 Megawatts he was scheduled to produce).

Additional costs to the mill included:

• Shutdowns of various sections of the plant to shed load so that the power demand charge would not be increased by the Public Utility
• The cost of pulling units off-line for one day to cool down
• One day to clean and then put the units back into operating condition (lost production)
• The contractor fee to do the actual cleaning job at $2,000 per unit

The water for cooling the condensers was obtained from a lake. The water was pulled from one section of the lake and returned to another. The lake circulation provided cooling for the water. Water temperatures at the facility reached 95 degrees Fahrenheit in the summer and 50 degrees Fahrenheit in the winter.

Applied Specialties recommended AS-8910 at a feed rate of 5 pounds per 1,000 gpm circulation rate. The feed would be for a one hour period per day. The cost for the treatment was calculated at $21,900 per year.

The plant had chlorine gas available at the condenser water and it was set up to maintain a 0.2 to 0.05 ppm free chlorine residual for 30 minutes each day. The AS-8910 was set to be introduced after the completion of the chlorine feed.

To minimize the environmental impact of the chlorine, treatment of the condensers was done one at a time. This allowed chlorinated to mix with unchlorinated water prior to the outfall and thereby reducing chlorine residuals.

The results of the treatment program using AS-8910 were as follows:

• No down time on the generators had been experienced due to condenser water problems.
• The mill has since been able to obtain the 30 Megawatts of desired production.
• The operating efficiency of the generators has increased and is now predictable. This now makes construction projections at the mill possible.
• The cleaning contractor normally hired to clean units during the annual inspection was canceled.
• Both condensers were clean when inspected during the annual inspection.

For more information on these and other fine ASI products, contact techservices@appliedspecialties.com At ASI, we produce results!