Industrial Cooling Water
Scale & corrosion inhibitor dosing for power and metallurgy cooling systems with online pH/conductivity monitoring.
Challenges
Open recirculating cooling systems concentrate continuously through evaporation: hardness, alkalinity, chloride and suspended solids rise, and warm water favours microbial growth. Too little scale and corrosion inhibitor leads to fouled or corroded exchangers and lost heat-transfer efficiency; too much simply wastes chemical and increases blowdown load. Late or irregular biocide dosing allows biofilm and Legionella risk to build.
Many sites still dose by hand once per shift and blow down by experience, so cycles of concentration drift and make-up and blowdown volumes are not controlled. Cooling-tower areas are usually outdoors, wet and dusty, which also sets requirements for the enclosure rating of pumps, analyzers and panels.
Our Approach
Cooling-water treatment rests on three controls: cycles of concentration, inhibitor dosing proportional to make-up, and biocide dosing on schedule or by ORP. A typical configuration:
1. Conductivity and blowdown: an online conductivity transmitter on the return line tracks concentration indirectly. Blowdown opens at the upper setpoint and closes at the lower one, holding cycles within the range set by water analysis.
2. Inhibitor dosing: a mechanical diaphragm metering pump paced by pulses or 4–20 mA from the make-up flowmeter keeps product concentration matched to make-up volume. Smaller systems can use a digital dosing pump for a wider turndown.
3. Biocides: oxidising biocide such as hypochlorite can be dosed against ORP or residual chlorine; non-oxidising biocide is normally slug-dosed on a timer from the panel.
4. Integrated skid or cabinet: inhibitor and biocide pumps, tanks, level gauges and controls are combined; outdoor units use suitably rated electrical components and weather protection.
5. Data: conductivity, pH, ORP and pump status can be passed to the DCS to track blowdown and chemical consumption.
Before design, please share the make-up water analysis, circulation rate, system volume, tower temperature difference and the treatment products currently in use, so setpoints can be agreed with your chemical supplier.
Practical notes: install the conductivity sensor where flow is steady and bubble-free, and clean it regularly. Interlock blowdown and make-up valves to avoid level problems. Oxidising biocides can affect some inhibitors, so follow your chemical supplier on compatibility, and protect outdoor equipment from freezing in winter.