26 | Plant & Works Engineering www.pwemag.co.uk August/September 2025 Energy & Environmental Management Focus on: Boilers, Burners & Controls The medium combustion plant directive (MCPD) has been in place for six years, with its impact steadily increasing across industries reliant on combustion technology. Introduced in December 2018, the legislation is designed to curb air pollution by regulating emissions of sulphur oxides (SO2), nitrogen oxides (NOx), and particulate matter from combustion plants ranging from 1 MW to 50 MW thermal input. The EU is home to approximately 143,000 medium combustion plants (MCPD), which serve critical functions such as electricity generation, domestic heating and cooling, and industrial heat or steam production. With a crucial compliance deadline approaching for larger existing installations now is the time for plant operators to ensure their equipment meets the required standards. Understanding the compliance timeline Under the MCPD, all new combustion plants commissioned on or after December 20, 2018, must already meet the directive’s emission limits. However, existing combustion plants face staggered deadlines based on their size: Plants with a thermal firing capacity ≥5000 kW must have complied by January 1, 2025. Plants between 1,000 kw and <5000 kW have until January 1, 2030. The variation in deadlines gives operators of smaller installations more time to assess their upgrade options. However, those running larger combustion plants must ensure compliance and avoid potential fines or operational disruptions. Objectives and broader regulatory impact The MCPD aims to protect both the environment and public health by limiting emissions from MCPS. It fills the majority of the regulatory gap between large combustion plants (>50 MWth) covered by the industrial emissions directive (IED) and smaller heating and hot water appliances (<400 kWth) regulated under the ecodesign directive. Additionally, the directive implements obligations arising from the Gothenburg protocol under the UNECE convention on longrange transboundary air pollution. The directive also allows for stricter national emission limits in areas where this can improve local air quality in a cost-effective way. To ensure continuous improvement, member states must report emissions data to the European commission in 2021, 2026, and 2031, with the commission assessing areas such as energy efficiency and carbon monoxide emissions as part of ongoing reviews. The role of burner technology in MCPD compliance For many combustion plant operators, the biggest challenge in meeting MCPD requirements lies in controlling NOx emissions. While strategies exist to reduce NOx, some traditional approaches can inadvertently decrease efficiency and increase carbon emissions - an outcome that runs counter to broader environmental and sustainability goals. Ultra-low NOx emissions refer to burner, boiler combinations that surpass standard low NOx emissions requirements, achieving even lower levels of NOx emissions. Ultra-low NOx burners employ advanced combustion technologies, such as internal and/or external flue gas recirculation, staged PWE looks at demystifying the technical aspects of MCPD compliance and how burner technologies can make it easier to meet regulatory requirements. Breaking down MCPD compliance combustion or selective catalytic reduction (SCR), to achieve reduced NOx emissions. Bernard Dawson, Technical Director at Riello Limited part of EMEA Residential and Light Commercial, highlighted how his company’s RS ULX burner can achieve NOx emissions of less than 40 mg/kWh without the use of external flue gas recirculation (ExFGR). Avoiding ExFGR reduces installation complexity, ongoing maintenance requirements, and associated costs. When applied with ExFGR, NOx emissions can be reduced even further. This illustrates how modern burner technology can help operators meet the Medium Combustion Plant Directive (MCPD) requirements while maintaining performance. In Riello’s case, its burner designs incorporate techniques such as: Flue gas recirculation (FGR) – in some models, Riello uses controlled recirculation of exhaust gases to lower combustion temperatures and limit NOx formation. Advanced premix and staged combustion – Riello’s combustion systems can precisely manage flame temperature and oxygen levels to achieve cleaner, more efficient combustion. Electronic modulation and digital control systems – Riello’s control platforms provide real-time monitoring and automatic adjustment to optimise efficiency while reducing emissions. While MCPD compliance is mandatory, it also presents an opportunity for businesses to future proof their facilities. Riello’s modular and retrofitcapable burner options for example can seamlessly integrate into existing systems, reducing emissions without compromising efficiency, and ensuring full MCPD compliance across all capacity ranges. The first of the MCPD deadlines has passed, and businesses operating combustion plants above 5000 kW must have already taken action to comply, but those below that threshold have to think – and act – soon to ensure compliance. For further information please visit: https://www.rielloburners.co.uk
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