System Overview
A large cement plant cooling tower uses cooling water to cool air compressors. The system water has high hardness, high alkalinity, and high suspended solids. Filtering is not an option because 80-85% of the particles are less than 5 microns in size.
Air compressors were fouling on a routine basis every three weeks. The compressors had to be shut down and cleaned, resulting in high maintenance, lost time and increased cost.
The previous CS-64 program used 280 ppm. Fouling was reduced but not eliminated. Our competition was making regular visits and the pressure was on to solve the problem or loose the business. A sample of deposit, analyzed by our lab, revealed that the deposits were a combination of calcium phosphate, calcium phosphonate and calcium carbonate.
The previous management strategy involved atomizing a fragrance into the air around the exhaust areas and had been an ineffective solution.
Treatment Program
CS-64 was replaced by CS-875, an OptidoseTM polymer, at 60 ppm, which yielded 6-10 ppm of free polymer. The feed rate for CS-64 was 283 ppm.
The target ppm for CS-875 is 45 ppm at $4.75 per pound. The target ppm for CS-64 was 225 ppm at $.94 per pound. The overall use cost calculates at virtually the same, but the benefits provided by the CS-875 program yield a positive Return on Investment as described in the "Results" section of this case study.
Results
CS-875 cooling tower dispersant showed great improvement over the use of CS-64 - very little compressor "fouling" was noted during the trial period. The CS-875 was effective in minimizing both phosphate and carbonate scaling. Over a period of six months, not a single air compressor was removed from service due to deposition and it has been noted that existing deposits are slowly removed. Overall use costs when utilizing CS-875 are comparable (possibly lower) to use costs when using CS-64. And at the same time, operating costs and lost time will be decreased substantially. Rochester Midland will continue to utilize CS-875 on the cement plant's cooling tower.
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