BIOLOGICAL GROWTH IN COLD WATER BASIN

[bumpjones]

Hello,
We put in two new cooling towers last year and we operated the cooling towers in tandem. When one chiller is running we run one condenser water pump and allow the condenser water to run over both towers. During operation of a single chiller we operate our towers at 1/2 of rated flow. When the second chiller starts, the second condenser water pump starts and both towers are subjected to rated flow. The problem is we are experiencing severe algae growth in the cold water basin. The rep says we need to spend a ton of money to install valve actuators to isolate one tower so that the towers are subjected only to rated flow. This will increase circulation in the cold water basin and allow for better mixing of the biocide. How can I be sure this will work?

Thanks,
bumpjones

 

[ChasBean1]

Not exactly my area, but I've seen several applications with analog-controlled three way cooling tower bypass valves. These send any percentage of the flow through the tower or bypassing the tower to maintain a given condenser water temperature. I think this issue could relate more to biocide treatment. Perhaps the chemical injection point should be split before and after the first tower basin to accommodate dilution so the the second basin sees an equal chemical concentration. I would guess that a majority of evaporation/makeup will usually take place in the first tower, leaving the second more susceptible to growth.

 

[quark]

Generally cooling towers are designed for a fixed L/G ratio and it is always better (for efficiency) to operate them at rated flow. How long is your cooling tower from chilling plant? (if it is not far, why can't you manually operate the valves?)

Check for areas of cooling tower which are in contact with direct sun light. (One important area is deck of the cooling tower)