PTQ Q3 2023 Issue

from the air through a cryogenic air separation unit (ASU) or with the use of membranes. Combustion thus takes place with nearly pure oxygen, resulting in a flue gas containing mainly CO₂ and water. Trace components like oxides of nitrogen (NOx) and sul - phur dioxide (SO₂) may be present. The CO₂ is purified by removing water and impurities. Gas analysis technologies are vital for effective and efficient carbon capture from each method. They deliver important measurements for emissions monitoring, safety, quality, and process control. To measure CO₂, CO, NOx, O₂, and SO₂ in the flue gas at several locations, a continuous emission monitoring system (CEMS) is needed. The use of CO₂ in the manufacture of fuels, carbonates, polymers, and other chemicals makes post-capture quality measurements essential. If captured from a process such as coal-fired power generation, it can contain traces of con - taminants like SO₂ and hydrogen sulphide (H₂S). In addition, to ensure safety, it is necessary to measure H₂S and H₂O in pipelines and to monitor CO₂ and O₂ in ambient air, keeping personnel safe in enclosed spaces around the pipeline or storage. Developing standards to measure sustainable suppliers While reducing emissions and ensuring reaction efficiency are key elements of strategies for clean air and net-zero carbon operations, it is also important to consider the organisations used to supply equipment and their own sustainability. One of the leading methods for establishing this in a measurable way is the EcoVadis rating. EcoVadis is an assessment platform for supplier sustainability ratings and provides important insight into a supplier’s Corporate Social Responsibility performance. It is based on ESG (environmental, social, and gover - nance) standards, using a variety of corporate performance evaluation criteria to measure a business’s impact on soci - ety, the environment, and the economy. The rating also determines how transparent and account - able an organisation is, including how they measure and demonstrate this with documents, data, and audited policies. Robust criteria have given EcoVadis global acceptance and credibility as the premier sustainability rating world - wide. The platform makes its assessment under four main headings: Environmental (including CO₂ emissions), Labour and Human Rights, Ethics, and Sustainable Procurement. This assessment is published on the EcoVadis database, which contains ratings for around 75,000 companies across the globe. A company’s presence and ranking on the EcoVadis database are increasingly studied by customers and inves - tors alike and are of growing importance – scoring well has a very positive benefit in terms of increased sales and increased credibility within the investment community. For example, last year Servomex achieved a gold rating from EcoVadis, proving its own commitment to sustainability throughout its gas analysis business.

Non-contact, photometric sensing technology provides the most effective and accurate measurement because gases containing SOx can be corrosive. Monitoring flue gas emissions helps determine the effi - ciency of a process and protects the environment. It also ensures that plant operators are complying with the neces- sary regulations. A continuous emissions monitoring system (CEMS) is required to measure all the necessary components of the flue gas to ensure compliance. This system must be capa - ble of offering the highest sensitivity and accuracy when dealing with multiple measurements for pollutants and greenhouse gases. Multi-component gas analysers are ideal for this applica - tion and, depending on the process, can either deliver all the necessary measurements in one device or form a key part of an integrated, comprehensive CEMS. Role of carbon capture processes One of the most effective ways to reduce the impact of industrial processes on the environment is to remove car - bon from the flue gas in a process known as carbon capture. As industries, organisations, and countries look to achieve net-zero carbon status, this form of gas clean-up is becom - ing more important than ever. Carbon capture and storage (CCS) technologies collect CO₂ emissions from power plants and heavy industry, then transport them by pipeline or ship for underground storage. Captured CO₂ can be used to manufacture fuels, car - bonates, polymers, and other chemicals, contributing to a circular economy – this is known as carbon capture and usage (CCU). However, since current CO₂ emissions greatly exceed the expectations of CO₂ usage, CCU is presently regarded only as a complementary alternative to CCS. There are three main types of carbon capture technology: post-combustion, pre-combustion, and oxyfuel combustion. Post-combustion carbon capture removes CO₂ from the flue gas after combustion – the flue gas is cleaned to remove trace components like sulphur dioxide (SO₂) and hydrogen chloride (HCl), which may interfere with the cap - ture process. The air is then purified, commonly with a molecular sieve, to remove water vapour, CO₂, and gaseous hydrocarbons. Various capture mechanisms can be applied, including phase separation, selective permeability, and sorption. Sorption is the most widely used mechanism and utilises chemical or physical solvents to separate the CO₂ from the gas stream. Pre-combustion carbon capture, as the name suggests, removes CO₂ before combustion of the fuel. It requires a carbonaceous fuel to be broken down into hydrogen (H₂) and carbon monoxide (CO), a mixture known as syngas. This syngas must be ‘shifted’ after it is cleaned to ensure highly efficient CO₂ capture. This ‘shift reaction’ yields heat and a gas stream with high CO₂ and H₂ concentrations. The CO₂ can then be removed with chemical and physical sol - vents, adsorbents, and membranes. Oxyfuel combustion carbon capture is based on denitrifi - cation of the combustion medium. The nitrogen is removed

PTQ Q3 2023