Heat Exchanger Scale and Fouling Control

Scaling is one type of fouling: hard mineral deposits, mostly calcium carbonate, that form when heat drives dissolved minerals out of the water and onto a surface. Fouling is the wider term. It also covers biofilm and marine growth, silt, and corrosion products. In practice they arrive together: scale gives biofilm a rough surface to hold on to, and biofilm traps silt.

Watch the numbers you probably already log. Differential pressure rises across the plate pack or tube bundle, outlet temperature or approach drifts from design, flow falls or pumps run harder for the same duty, and cleaning comes round sooner. Slime, shells or grit at the strainers are an early sign too.

At a Hong Kong seawater plant, the untreated plate heat exchanger ran at higher differential pressure and lower flow than its treated twin, and was found blocked to a depth of 90cm (3 ft).

It depends on the water, the temperature and the duty, so there is no single interval, and your manufacturer’s inspection schedule still applies. The useful question is what stretches the interval. A Middle East hospital went from acid cleaning every three to four months to none in 17 months, and UBC Baton Rouge‘s fresh water generator ran three times longer between openings than it had on chemicals.

The usual options are mechanical cleaning (strip-down, brushing, jetting) or chemical cleaning with acid, both with the exchanger offline. HydroFLOW® takes a slower route: once less new scale is forming, existing deposits soften and loosen over months. At a Ukrainian plant, existing scale was released progressively and the inspected flange showed no scale at ten months. On MV Hoegh America, only loose scale was left on the plates and cleaning took under two hours instead of 24 to 48.

If an exchanger is badly blocked today, clean it first, then use HydroFLOW® to help keep it clean.

There are three physical routes. Take the hardness out before the exchanger (softening or RO), wipe the surfaces in service (automatic tube cleaning, tubes only), or change how minerals and biofilm behave so that less of either bonds, which is what HydroFLOW® does.

The strongest evidence for that last route is a controlled comparison: in Hong Kong, a treated and an untreated plate heat exchanger ran side by side on the same seawater for six months, and the treated one stayed largely open with 14–18% more flow. Most sites keep some chemistry. The aim is less of it, measured on your own records.

Plate and shell-and-tube: yes, and the case studies cover both, from gasketed plate packs and marine fresh water generators to tube bundles, chiller condensers and power-station condensers.

Brazed plate exchangers cannot be opened for cleaning, which makes keeping scale out of them more valuable, but we have no brazed plate case study yet, so we make no performance claim for them. Air-cooled exchangers have no water side to treat, so HydroFLOW® does not apply.

On the supply pipe upstream of the exchanger. The unit installs around the outside of the existing pipe, and the signal travels through the water in both directions, so one unit can cover several exchangers on the same line. A Ukrainian plant protects two plate heat exchangers with one K40, and Enaex in Chile treats every branch of its seawater system from one unit 126 m upstream. Unit size depends on pipe diameter and flow.

Yes. Nothing is cut into the pipe and nothing is drained, so the exchanger keeps running while the unit is fitted. A Middle East hospital installed two units with no downtime or plumbing changes, and MGEN Trois-Épis in France fitted twelve in one day without interrupting its hot water supply. That also makes a trial simple: one unit upstream of one exchanger, measured against your own logs.

Not by default, and your water treatment contractor should make that call on your data. Some sites have reduced or stopped chemicals as a site result: Imperial Oil cut antiscalant from 2.0 to 0.0 ppm over a 12-month trial, and several ships ran their fresh water generators without dosing.

Closed-loop corrosion inhibitor stays where it is specified, and in food plants CIP frequency is set by your food-safety plan. Tims Dairy halved its milk-line cleans, a decision the site made on its own checks.

Scepticism is fair. Results vary, many low-cost devices are sold with no evidence behind them, and a conditioner does not remove minerals the way a softener does. HydroFLOW® is not a magnet or a wire coil: it induces a patented ~150 kHz signal into the water, and units are sized to the pipe and the duty.

The evidence we would ask you to weigh is a controlled comparison. On the same Hong Kong seawater circuit, the treated plate heat exchanger stayed largely open and carried 14–18% more flow, while the untreated one blocked to a depth of 3 ft. Then test it on one exchanger of your own.

It can, for a while, so plan for it. As existing scale and biofilm loosen, the material travels with the water to strainers, filters and the exchanger itself, and plate channels are narrow. Check strainers more often in the first weeks, and inspect the plate pack or tube sheet at the next opportunity after install.

Sites have recorded this clearing phase: at a Kyiv brewery, filter deposits softened enough to rinse away, and at the Ukrainian plant, deposits were released gradually into the flow.