Overview
ISO/TS 21152:2024 - "Guidance on water conservation techniques of circulating cooling water in thermal power plants" provides technical and management guidance for reducing freshwater use in indirect open recirculating cooling systems. Applicable to coal, oil, natural gas and biomass‑fired thermal power plants, the Technical Specification covers systems that use surface water, groundwater, reclaimed water or treated domestic sewage as make‑up water and that apply physicochemical water treatment to increase cycles of concentration and improve water use efficiency.
Key topics and technical requirements
- Water quality recommendations: guidance on acceptable make‑up water and circulating cooling water parameters (example ranges include pH 7.5–8.8; TSS ≤100 mg/L; TDS ≤5 000 mg/L; conductivity ≤8 500 μS/cm; NH3‑N ≤10 mg/L, ≤5 mg/L for copper condensers).
- Cycles of concentration: definition, calculation methods and limits for selecting appropriate cycles to balance water savings with scaling/corrosion risk.
- Treatment technologies: physicochemical options to increase cycles of concentration, including lime softening, weak acid cation resin treatment, membrane treatment, scale and corrosion inhibition, microbial control, and side‑stream filtration.
- Cooling tower guidance: operational guidance for reducing bleed/blowdown and minimizing evaporative and drift losses while ensuring system safety and heat‑exchange efficiency.
- Monitoring and instrumentation: recommendations for detection, measurement and control systems to manage water quality and dosing strategies.
- Management practices: water utilities management, selection of low‑toxicity/biodegradable chemicals, regulatory awareness and risk‑based operation.
- Supporting annexes: informative annexes include dynamic simulation tests for scale/corrosion inhibitors, laboratory evaluation tests, cycles‑of‑concentration calculations, side‑stream filtration sizing, and intermittent dosing models.
Practical applications
- Optimize make‑up water selection and pre‑treatment to enable higher cycles of concentration and lower freshwater withdrawals.
- Design or upgrade water treatment trains (membranes, softening, inhibitors, filtration) for cooling towers and condensers.
- Improve operational controls, dosing and monitoring to reduce blowdown, scaling and corrosion while maintaining plant reliability.
- Support compliance with environmental regulations and corporate water‑conservation targets.
Who should use this standard
- Plant owners and operators, water treatment and process engineers
- Cooling system designers and EPC contractors
- Environmental and water‑resources managers, regulatory bodies
- Technical consultants, chemical suppliers and instrumentation vendors
Related standards
- ISO/TC 282 (Water reuse) guidance context; cycles of concentration definition cites ISO 16784‑2:2006.
