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ISO 27919-2:2021 — Stable Performance of Post-Combustion CO2 Capture Plants
Evaluation procedure for availability, reliability, and maintainability of PCC plants integrated with power plants
1. Overview of ISO 27919-2:2021
ISO 27919-2:2021 provides an evaluation procedure to assure and maintain reliable, stable performance of post-combustion CO2 capture (PCC) plants integrated with power plants. Building upon the KPI framework established in ISO 27919-1, this second part addresses the critical operational aspects of availability, reliability, and maintainability (ARM) that determine the practical value of PCC facilities. The standard was developed by ISO/TC 265 and represents the first international standard to provide a systematic approach for evaluating the long-term operational performance of PCC plants.
While ISO 27919-1 focuses on “how well does the PCC plant perform when running,” ISO 27919-2 addresses “how often and how reliably can the PCC plant run” — equally important for the economic viability of CCS projects.
The standard applies to PCC plants using chemical absorption technology, the same scope as ISO 27919-1. It provides definitions, guidelines, and supporting information for evaluating and reporting PCC plant performance with respect to basic design items and operational results, using feedback from reference plants to ensure sustained performance.
2. Reliability, Availability, and Maintainability Framework
2.1 Defining ARM for PCC Plants
The standard establishes a comprehensive framework for evaluating PCC plant availability, reliability, and maintainability. Availability represents the fraction of time the PCC plant is capable of producing CO2 product at the required quality and rate. Reliability measures the probability that the PCC plant will operate without failure for a specified period. Maintainability quantifies the ease and speed with which the plant can be restored to operation after a failure.
| ARM Element | Definition | PCC Plant Context |
|---|---|---|
| Availability | Fraction of time capable of CO2 production | Accounts for planned and unplanned outages |
| Reliability | Probability of operation without failure | Failure modes include solvent degradation, corrosion, foaming |
| Maintainability | Ease and speed of restoration after failure | Includes solvent replacement, column cleaning, component replacement |
2.2 Spatial and Temporal Boundaries
The standard defines evaluation boundaries considering both spatial and temporal dimensions. Spatially, the evaluation covers all PCC plant equipment including absorption columns, stripping columns, heat exchangers, pumps, and the CO2 compression system. Temporally, the evaluation covers the entire operational lifecycle from commissioning through routine operation to decommissioning. The standard distinguishes between three categories of unavailability: planned maintenance, unplanned maintenance, and external causes.
PCC plant reliability is significantly influenced by the quality of the flue gas from the host power plant. Variations in flue gas composition, temperature, and flow rate due to power plant load changes can stress PCC equipment and reduce reliability.
3. Evaluation Procedure for Design and Operation
3.1 Basic Design Phase Evaluation
During the basic design phase, the standard requires a systematic evaluation of the PCC plant configuration to assess potential reliability issues. This includes analysis of equipment selection, redundancy requirements, material selection, and process control strategies. The evaluation follows a structured procedure outlined in Annex A, with six process steps addressing everything from establishing performance requirements to verifying technology readiness through technology qualification procedures (Annex C).
3.2 Operational Phase Evaluation
The standard provides detailed methodologies for determining reliability and availability during actual operation. Key parameters include the basic load pattern, steady-state operation assessment, transient operation during start-up and shutdown, emergency operations, and planned maintenance activities. The standard requires systematic recording and analysis of all operating events, including the duration and cause of each outage event.
The operational phase evaluation creates a continuous improvement loop — operational data feeds back into design improvements, maintenance planning, and operational optimization, progressively enhancing PCC plant performance.
4. Key Performance Indicators for ARM Reporting
4.1 PCC Plant Capacity Availability
The standard defines PCC plant capacity availability (PCA) as the ratio of actual CO2 production to reference production capacity over a specified time period. This KPI accounts for both the frequency and duration of outages, providing a comprehensive measure of plant productive performance. Product CO2 producibility (PCP) is a related metric that considers the ability to deliver CO2 at the required quality specifications.
4.2 Time-Based Availability Metrics
Time availability metrics measure the fraction of calendar time during which the PCC plant is available for operation, regardless of production rate. The on-stream factor quantifies the fraction of time the plant is actually processing flue gas and producing CO2. Schedule compliance measures the ability to meet planned CO2 delivery commitments.
| KPI | Formula Basis | Typical Target |
|---|---|---|
| PCA (Capacity Availability) | Actual production / Reference production | > 90% |
| Time Availability | Available time / Calendar time | > 95% |
| On-Stream Factor | Operating time / Calendar time | > 85% |
| Schedule Compliance | Delivered CO2 / Planned CO2 delivery | > 95% |
5. Maintenance Implications
The standard discusses maintenance strategies for PCC plants, addressing the unique challenges of CO2 capture equipment. Key maintenance considerations include solvent management (reclaiming, filtration, and replacement), corrosion management (particularly in the absorber and stripper columns), heat exchanger cleaning to maintain thermal performance, and compressor maintenance. The standard emphasizes that proactive maintenance planning based on reliability data is more effective than reactive maintenance for maximizing PCC plant availability.
For maximum availability, PCC plant operators should implement condition-based maintenance with real-time monitoring of critical parameters including solvent concentration, degradation products, corrosion rates, and heat exchanger fouling factors.
6. Engineering Insights for Reliable PCC Operation
From ISO 27919-2:2021, key engineering lessons include:
- PCC plant availability is as important as capture efficiency for economic viability — a plant with 95% efficiency but 80% availability produces less CO2 reduction than one with 90% efficiency and 95% availability.
- Solvent degradation and its management is the single most common cause of unplanned PCC plant outages.
- Designing for adequate redundancy in critical equipment (solvent circulation pumps, heat exchangers) can substantially improve availability at modest capital cost increase.
- The standard’s technology qualification procedure (Annex C) provides a structured approach for qualifying new solvents or equipment configurations before full-scale deployment.
- Integration with power plant operations requires careful coordination — PCC plant startups and shutdowns must be synchronized with power plant operations to minimize both plant disruption and emission events.
ISO 27919-2:2021 completes the PCC performance evaluation framework by adding the operational reliability dimension to the KPI-focused approach of ISO 27919-1. Together, these standards provide comprehensive guidance for designing, evaluating, and operating reliable PCC plants.
7. Frequently Asked Questions
Q: How does ISO 27919-2 relate to ISO 27919-1?
A: ISO 27919-1 defines the KPIs for PCC plant performance; ISO 27919-2 provides the procedure for ensuring that the designed performance is achieved and maintained through reliable operation.
A: ISO 27919-1 defines the KPIs for PCC plant performance; ISO 27919-2 provides the procedure for ensuring that the designed performance is achieved and maintained through reliable operation.
Q: Does the standard apply to PCC plants with different solvent systems?
A: Yes, the ARM evaluation methodology is solvent-agnostic and applies to all chemical absorption-based PCC systems covered by ISO 27919-1.
A: Yes, the ARM evaluation methodology is solvent-agnostic and applies to all chemical absorption-based PCC systems covered by ISO 27919-1.
Q: What is the recommended availability target for a PCC plant?
A> While site-specific factors determine the target, the standard’s KPIs suggest that a well-designed PCC plant should achieve over 90% capacity availability.
A> While site-specific factors determine the target, the standard’s KPIs suggest that a well-designed PCC plant should achieve over 90% capacity availability.
Q: How should unavailability due to host power plant outages be categorized?
A> The standard categorizes this as external-cause unavailability and requires separate reporting to distinguish PCC-caused outages from power plant-caused outages.
A> The standard categorizes this as external-cause unavailability and requires separate reporting to distinguish PCC-caused outages from power plant-caused outages.
