Replacement of Chlorine Gas at an Electrical Power Generating Station
History
A large coal fired electrical power station in southern Indiana has historically used chlorine gas for control of biological growth in two cooling tower systems serving 531.5 MW and 565 MW steam turbine generators. Due to the increasing restrictions on use of chlorine gas by the USEPA, DHS, and OSHA; the station desired to convert to an alternative biocide.
Control of biological growth in both cooling systems with chlorine gas was judged to be acceptable using four slug doses per day. System specifications are:
| Unit 3 | Unit 4 | |
| flow rate, gpm | 171,560 | 190,330 |
| system volume, gal | 1,870,000 | 1,650,000 |
| makeup rate, gpm | 7,533 | 7,133 |
| delta T, deg F | 33 | 33 |
| condenser tube metallurgy | 304 | stainless steel |
Unit 4 Cooling Tower
The two cooling tower systems are normally operated at 4 cycles with addition of 0.75 mg/l HEDPA phosphonate and pH controlled to 8.2 by addition of sulfuric acid for scale control. Makeup water is taken directly from the White River with no pretreatment.
Following our development of the ElectroBrom Biocide System tm in 2003, we recommended that the chlorine gas use be replaced with two Model EBG-40 units feeding a dose tank. Station management agreed and the recommended equipment was installed and started up in March, 2004.
Two EBG-40 units with dose tank and pump.
Results
Biological control, with the EBG-40 units replacing the chlorine gas has been judged to be visually the same, or better. This observational data has been verified by routine daily ATP and bio test strip test data which has shown equal, or better, results than during operation with chlorine gas.
The station is pleased that the ElectroBrom Biocide System has controlled biological growth while eliminating a safety and regulatory problem at an operating cost increase of only 28% over chlorine gas.
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