Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of ISO document should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

ISO draws attention to the possibility that the implementation of this document may involve the use of (a) patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s) which may be required to implement this document. However, implementers are cautioned that this may not represent the latest information, which may be obtained from the patent database available at www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.

Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISO's adherence to the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.

This document was prepared by Technical Committee ISO/TC 265, Carbon dioxide capture, transportation and geological storage.

Any feedback or questions on this document should be directed to the user’s national standards body. A complete listing of these bodies can be found at www.iso.org/members.html.

Introduction

Carbon dioxide capture and storage (CCS) is a suite of technologies to reduce carbon dioxide (CO₂) emissions into the atmosphere, as a central aspect of reducing overall greenhouse gas emissions that are causing climate change. CCS is widely recognized to play a crucial role in achieving deep and large-scale decarbonization in a short time frame in the power and industrial sectors. Among several CO₂ capture pathways, post-combustion CO₂ capture (PCC) is the most mature and viable, capable of reducing CO₂ emissions from combustion processes in the energy-related and industrial sectors. Chemical absorption using reactive liquids is a proven technology and has been widely developed in numerous PCC facilities. Various absorption liquids, such as amines, potassium carbonate, aqueous ammonia solutions, amino-acid salt solutions and mixtures of these reactants, have been adopted for PCC applications.

The performance of absorption liquids is one of the key factors influencing the cost and the energy consumption in a PCC process, thereby influencing its commercial application and its net greenhouse gas impact. Understanding the key performance parameters and physical and chemical properties of absorption liquid is essential, not only for screening of promising absorption liquids, but also for process engineering design and evaluating PCC plant performance during operation.

Specifically, accurate monitoring of CO₂ loading and absorbent concentration in the absorption liquid will guide parametric measurement, optimization, commissioning and operation of the PCC plant. Understanding the absorption capacity helps in selecting the appropriate absorption liquid for CO₂ capture, and optimizing the process conditions using information from vapour-liquid equilibria. A larger cyclic loading of CO₂ in the absorption liquid means that less absorption liquid needs to be circulated, leading to lower energy consumption for pumping, heating and cooling. Absorbent volatility is one of the factors leading to absorbent loss. The heat of absorption of CO₂ is a primary factor influencing the energy required for regenerating absorption liquids. The viscosity of absorption liquids can affect absorber flooding, and electricity consumption for pumping. A higher viscosity of the absorption liquid also reduces the heat transfer coefficient for the heat exchanger, meaning more heat exchanger area is required to achieve the same heat duty. It also decreases the absorption and mass transfer between gas and liquid. The absorption rate of absorption liquids impacts the capital costs of the PCC process. A higher absorption rate of the absorption liquids enables a shorter packing height in CO₂ capture, which reduces the sizes of the absorber and desorber. The density and viscosity are physical and chemical properties of absorption liquids. The thermal conductivity and specific heat capacity are important thermophysical properties to understand the heat transfer process in absorption liquid-based CO₂ capture process.

Given the large and diverse impact of absorption liquids on various aspects of PCC plant performance, an ISO standard for evaluating and characterizing the key performance parameters of absorption liquids is required and that would complement the standards for CO₂ capture, ISO 27919-1 and ISO 27919-2 . Previously, ISO 27919-1 was developed as a guideline for measuring, evaluating and reporting the performance of a PCC plant integrated into a power plant. It provides a general methodology for calculating specific key performance indicators for the PCC process within the entire power system. ISO 27919-2 was developed to specify an evaluation procedure to ensure and maintain the stable performance of the PCC process integrated into a power plant during operation, from a commissioning perspective.

The measurement and evaluation of the key physical and chemical characteristics of absorption liquids, as defined in this document, are essential. This will benefit technology developers for the subsequent PCC process design, optimization, performance monitoring and plant operation.

1 Scope

This document provides definitions, guidelines and supportive information for the key performance parameters and their characterization methods of absorption liquids used in post-combustion CO₂ capture. It covers common methodologies to measure and calculate specific key performance parameters of the absorption liquids.

The absorption liquids for post-combustion CO₂ capture covered by this document are chemically reactive liquids, such as amine solutions, potassium carbonate solutions, aqueous ammonia, amino-acid salt solutions and mixtures of these reactants. Other absorption liquids based on different principles for CO₂ capture are not covered.

The key performance parameters considered in this document relate to the design and operation of absorption liquid-based post-combustion CO₂ capture processes, as well as equipment such as absorber and desorber columns, reboilers and other heat exchangers.

The key performance parameters are:

primary parameters, such as rich and lean CO₂ loading, absorbent concentration, absorption capacity, heat of absorption, absorption rate and absorbent volatility;

secondary parameters, such as cyclic loading, that are directly derived from the primary parameters, or combined with other physical measurements, as in the case for the absorbent loss rate.

In addition, physical and chemical properties such as density, viscosity, pH, thermal conductivity and specific heat capacity are described. These properties are essential for understanding the key performance parameters of the absorption liquids.

This document also:

establishes key performance parameters (see Clause 4), physical and chemical properties of absorption liquids, and their calculation methods, and provides a common way of reporting them;
specifies the general requirements for the absorption liquid characterization in laboratory measurement and field testing (see Clause 5);
provides the requirements for the instrumentation to be installed or used, and guidelines for the characterization methods (see Clause 6);
provides information on the characterization methods of absorption liquids, describing all stages of test preparation, set-up and execution (see Annexes A to I), as well as guidance on sampling absorption liquids.

NOTE While key performance parameters of absorption liquids are important process indicators for post-combustion CO₂ capture, factors such as process design, equipment design and manufacturing, economics and safety are also considered for a comprehensive evaluation of post-combustion CO₂ capture technology.

The document does not provide guidelines for benchmarking or comparing absorption liquids for post-combustion capture processes, nor does it offer methods to assess different technologies or projects, or specify methodologies for process engineering design. Additionally, the document is not intended to compel technology owners to disclose any intellectual properties related to their proprietary absorption liquids.

The document does not cover all available and emerging characterization methods for the key performance parameters considered in this document.

2 Normative references

3 Terms, definitions, abbreviated terms and symbols

3.1 Terms and definitions

3.2 Abbreviated terms

3.3 Symbols

4 Evaluation of performance parameters

4.1 General

4.2 Primary performance parameters

4.3 Secondary performance parameters

4.4 Physical and chemical properties

5 General for the characterization of absorption liquids

5.1 Laboratory measurements and field testing

5.2 General requirement

6 Instrument and characterization methods

6.1 General

6.2 Instrument classification

6.3 Calibration of instrument

6.4 Evaluation of measurement uncertainty

6.5 Competence in characterization methods

Bibliography