Overview
SIST EN ISO 21654:2021 - Solid recovered fuels: Determination of calorific value (ISO 21654:2021) specifies a standardized laboratory method to determine the gross calorific value of solid recovered fuels (SRF) measured at constant volume and corrected to the reference temperature of 25 °C. Measurements are performed in a combustion vessel calorimeter calibrated by combustion of certified benzoic acid. This European adoption of ISO 21654:2021 supersedes EN 15400:2011 and aligns fuel‑calorific testing across accredited laboratories.
Key topics and technical requirements
- Scope and principle: Defines gross and net calorific value concepts and the calorimetric principle for SRF.
- Laboratory conditions & reagents: Specifies environmental and reagent controls required for repeatable calorimetry.
- Apparatus: Requirements for combustion vessel calorimeters (adiabatic, isoperibol, static‑jacket, automated systems) and auxiliary equipment.
- Sample preparation: Procedures to prepare representative SRF test samples to minimize variability.
- Calorimetric procedure: Step‑by‑step guidance for assembling the calorimeter, initiating combustion, measuring temperature rise and analysing combustion products.
- Calibration: Calibration of effective heat capacity using certified benzoic acid, determination of valid working range and ancillary contributions.
- Calculations & correction: Methods to calculate gross calorific value, transform to other bases, and compute net calorific value at constant pressure.
- Precision & reporting: Repeatability and reproducibility considerations, required test report elements and example calculation annexes.
- Normative and informative annexes: Detailed guidance for different calorimeter types, automated systems, ash contributions, calculation examples, checklists and environmental considerations.
Practical applications
- Accurate measurement of calorific value for SRF used in waste‑to‑energy, cement kilns, industrial co‑firing and other thermal processes.
- Quality control and fuel specification: supports contractual energy content verification and commercial trading of SRF.
- Regulatory compliance and reporting: provides harmonized test methods for environmental permits and emissions modelling.
- Process optimisation and combustion performance assessment: informs boiler/combustor tuning, fuel blending and process control.
Who should use this standard
- Accredited testing laboratories and calorimetry specialists
- SRF producers and fuel suppliers for product certification
- Waste‑to‑energy plants, cement industry and industrial users evaluating fuel quality
- Environmental and regulatory bodies overseeing energy reporting and compliance
- Quality assurance, R&D and metrology teams involved in fuel analysis
Related standards
- Supersedes EN 15400:2011
- Developed by ISO/TC 300 (Solid recovered materials) in collaboration with CEN/TC 343
- Relevant ICS code: 75.160.10 (Solid fuels)
Keywords: solid recovered fuels, calorific value, gross calorific value, calorimeter, combustion vessel calorimeter, benzoic acid calibration, ISO 21654, SIST EN ISO 21654:2021, fuel analysis, net calorific value.