SCR optimization

SCR optimization

Compliance with IMO Tier III NOx limits requires more than certified engine performance. In real operation, Selective Catalytic Reduction (SCR) systems can lose effectiveness due to catalyst degradation, incorrect urea dosing, or unintended bypass operation leading to higher emissions and increased compliance risk.

Meeting these requirements depends on effective NOx reduction strategies, such as SCR and Exhaust Gas Recirculation (EGR), each suited to different vessel and operating conditions.

Without continuous measurement, deviations in SCR performance often remain undetected until non-compliance is identified by regulators or Port State Control.

Using CEMS technology for optimizing SCR performance

Reducing NOx emissions to meet IMO Tier III limits depends on effective emission control technologies, primarily exhaust gas recirculation (EGR) and selective catalytic reduction (SCR).

The exhaust after-treatment technology SCR removes NOx by injecting urea into the exhaust stream, but its performance relies on correct dosing and operating conditions.

Traditional dosing based on engine load does not always reflect actual exhaust conditions, which can reduce efficiency, particularly during transient operation.

By using a marine continuous emission analyzer downstream of the SCR, real-time NOx measurements can be used to optimize urea dosing. This enables more precise control and improved performance based on the actual exhaust output from the SCR.

The impact of poor SCR performance

Poor SCR performance can lead to increased operational costs, reduced efficiency, and a higher risk of non-compliance. Without accurate emissions data, maintaining optimal dosing and system control becomes difficult resulting in wasted resources, unstable performance, and potential system damage.

Higher operating costs

Excessive urea consumption and inefficient system operation.

Reduced efficiency

Inconsistent NOx reduction across varying engine loads.

Increased compliance risk

Greater likelihood of exceeding emissions limits.

System inability and damage

Risk of fouling, deposits, and long-term component degradation.

Optimized SCR performance with Danfoss IXA CEMS technology

By delivering fast and reliable ppm measurements, MES 1001 supports simplified SCR control and helps enable reduced urea consumption.

Used for monitoring or closed‑loop control, MES 1001 enables optimized SCR performance:

• Optimized urea dosing based on real NOx reduction demand
• Optimized NOx output across steady and transient engine loads
• Direct NH3 slip measurement for SCR condition monitoring
• Early detection of SCR degradation or abnormal operation
• Reduced risk of ammonium bisulfate formation, avoiding fouling and back‑pressure increase

Yanmar – Cost efficient selective catalytic reduction process with marine emission monitoring

Yanmar – the leading Japanese manufacturer of marine engines and propulsion solutions has, through a long-term partnership with Danfoss IXA, tested the MES 1001 sensor for NOx, SO2, and NH3 in a closed-loop application for its Selective Catalytic Reduction (SCR) technology.

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