Case study

Cooling tower blowdown optimization

Cooling towersWaterManufacturing: automotive, plastics & rubberBuilding Materials, Concrete & Aggregates

Blowdown was controlled by a timer rather than conductivity, causing usable water to be discharged unnecessarily.

A plastics factory’s cooling tower discharged usable water on a fixed timer. We bring make-up flow, blowdown and basin conductivity together so the team can base blowdown on the water’s condition.

What the data showed

Explore the chart to inspect the readings.

Cooling tower blowdown optimization
makeup to evaporation, 62 L/minmakeup to blowdown, 38 L/minmakeup to unaccounted, 14 L/minrecovered to evaporation, 11 L/minmakeup to drift, 6 L/minMake-up water120 L/minRecovered condensate11 L/minEvaporation73 L/minBlowdown38 L/minUnaccounted14 L/minDrift6 L/minMake-up water to Evaporation: 62 L/min, 47% of total flowMake-up water to Blowdown: 38 L/min, 29% of total flowMake-up water to Unaccounted: 14 L/min, 11% of total flowRecovered condensate to Evaporation: 11 L/min, 8% of total flowMake-up water to Drift: 6 L/min, 5% of total flowMake-up water120 L/min92% of totalRecoveredcondensate11 L/min8% of totalEvaporation73 L/min56% of totalBlowdown38 L/min29% of totalUnaccounted14 L/min11% of totalDrift6 L/min5% of total
TOWER WATER BALANCE · MAKE-UP TO EVAPORATION, DRIFT AND BLOWDOWN

Background

A plastics manufacturing factory uses a cooling tower with blowdown controlled by a timer. Each scheduled discharge sends water out of the system and requires make-up water to replace it. Our review follows those flows alongside the water condition in the basin to see what is driving the discharge.

The problem

A fixed timer follows a schedule regardless of the measured conductivity. The tower can therefore discharge water while it is still usable. The make-up total captures the replacement water, but that figure alone does not show how the timing of blowdown relates to the condition of the water leaving the system.

How we found it

We use flow meters on the make-up and blowdown lines, with conductivity monitoring in the tower basin. Cycles-of-concentration trending gives the team another view of how the tower is operating. Reading the flows and conductivity together connects the discharge pattern with the condition that should inform the blowdown decision.

What changed

Blowdown moves from a fixed timer to a measured conductivity threshold. The team can review the point at which discharge occurs alongside the make-up demand.

The lesson

Keep flow and conductivity readings together after changing the setting. Operations and maintenance can then check when blowdown occurs, how much make-up water follows and whether discharge matches the threshold.

What changed

Before

Blowdown on a timer

After

Blowdown on a measured conductivity threshold

1 setpointchanged

Blowdown moved from a fixed timer to a measured conductivity threshold.

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