Optimising cooling water treatment

Water & steam · Industrial practice · Updated 2026-06-01

Cooling water treatment optimisation is the tuning of chemistry, cycles of concentration and dosing in an open recirculating system to control scale, corrosion and biofouling at the lowest water and chemical use. It balances heat-transfer protection against blowdown and makeup, because over-treating wastes water and under-treating fouls the very surfaces it should protect.

What it is

An open cooling tower concentrates dissolved solids as it evaporates, so treatment manages that concentration and adds inhibitors to stop scale, corrosion and biological growth on heat exchangers and tower fill. Optimisation means finding the highest safe cycles of concentration and the leanest effective dosing, rather than running conservative chemistry that throws away treated water and chemical.

Why it is done

Scale and biofilm are thermal insulators: a thin deposit on a heat-exchanger tube can lose more heat transfer than weeks of fouling elsewhere, and corrosion both leaks and seeds further fouling. Yet pushing cycles too high precipitates hardness and forces excessive blowdown. Getting the balance right protects condensers and process coolers, cuts makeup water and chemical spend, and avoids the unplanned cleans that follow a fouling event.

How it is done

The water balance is established first — evaporation, drift and blowdown — and current cycles of concentration are calculated from a conserved ion such as conductivity. The makeup water analysis sets the scaling and corrosion limits, defining how high cycles can safely run. Inhibitor and biocide programmes are matched to those limits and dosed on conductivity and timed control, with corrosion coupons and heat-exchanger inspection confirming the result. Cycles are then raised in steps while monitoring deposition and corrosion, settling at the point just below the scaling threshold.

1. Establish water balance
2. Calculate cycles
3. Set scaling limits
4. Match dosing programme
5. Raise cycles in steps
6. Confirm with coupons

What to watch for

The recurring errors are running needlessly low cycles ‘to be safe’, which wastes water and chemical, and chasing high cycles without checking the scaling indices, which precipitates hardness onto hot surfaces. Neglected biocide control lets biofilm establish under the scale inhibitor's notice, and infrequent coupon checks hide creeping corrosion until a tube leaks.

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Related topics

Cooling Tower Efficiency and Reliability · Heat Exchanger · Heat Loss

Common in: Power Generation · Chemicals · Food Processing · Steel & Metals

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