Ecoexhaust designed, manufactured and supported the installation of Selective Catalytic Reduction (SCR) systems on three reefer vessels operated by Fjord Shipping AS.

The retrofit achieved approximately 90% NOx reduction, corresponding to IMO Tier III emission levels, on 2,190 kW MAN two-stroke main engines originally manufactured in 1990.

Project Scope

The project scope covered the retrofit of existing vessels with marine SCR systems, designed to operate within the technical constraints of legacy two-stroke engines and limited available space.
The installation was coordinated with the vessels’ scheduled class renewal to minimize off-hire time.

Engineering Assessment

A feasibility study was conducted to define the relevant engine operating conditions and installation constraints, including:

• Exhaust gas temperature range
• Exhaust gas mass flow
• Available space in the engine room and funnel

To accurately confirm installation feasibility, 3D laser scanning was performed in the funnel area, where space limitations were most critical.

System Design

Based on the collected data, Ecoexhaust developed a custom SCR system and adapted the main engine exhaust configuration accordingly.

The design included:

• Compact SCR reactor geometry suitable for limited funnel space and restricted exhaust gas backpressure
• Bypass valves allowing engine operation without SCR, reducing catalyst exposure during non-SCR operation
• Optimized exhaust gas distribution upstream of the catalyst

CFD calculations were used to verify the static mixer design and confirm uniform flow distribution across the catalyst blocks.

Manufacturing, Installation and Commissioning

The SCR systems were manufactured by Ecoexhaust and delivered to the shipyard during the vessels’ class renewal period. Installation was carried out under the supervision of Ecoexhaust engineers, followed by:

• System calibration
• Sea trials under operational conditions

Ecoexhaust participated in the certification process with DNV, supporting the documentation required for emission compliance and NOx reporting.

Results

• Approx. 90% NOx reduction achieved
• IMO Tier III-equivalent emission performance
• Reduced NOx tax exposure under the Norwegian scheme
• Successful SCR retrofit on legacy two-stroke engines
• No significant increase in vessel downtime

SCR control system

SCR reactor in funnel