Pioneering exhaust with silencer and SCR

One of the innovative projects that we are currently involved in involves creating a marinised IMO TIER III-certified exhaust system for a leading Italian yard. In close cooperation with our partners we have developed a fully custom module silencer/SCR system that will combine the working principles of Selective Catalytic Reduction – which eliminates most harmful NOX compounds – with highly efficient noise reduction.

The silencer/SCR module is fitted on MarQuip’s effective water-injection piece with underwater exhaust, and achieves a noise reduction of 35 dB(A) while complying fully with IMO TIER III NOX limitations. The marine-proof new system successfully fulfilled a range of requirements linked to the client’s needs and the engine specifications.

The first challenge was staying within the maximum backpressure specified by the engine manufacturer. This was particularly complicated by the fact that adding after-treatment equipment to exhaust systems can have the adverse side effect of increasing backpressure. Our specially designed underwater scoop helped reduce backpressure significantly while staying well within the designated dimensions.

The second step was noise reduction. This goal was achieved by utilising the high-frequency noise reduction capabilities of the SCR unit and complementing them with a dedicated low and medium-frequency silencer part.

The third and last step was to make the SCR unit fit for marine use. Our engineers knew from experience that pressure pulses in waves of up to 500 mbar in heavy weather cause equipment to undergo low cycle fatigue. They carried out strength calculations which showed that a standard SCR unit fails after only 600 pressure pulses. The design was strengthened accordingly, and its ability to withstand pressure pulses significantly increased. The new solution complies with the highest marine standards.

Production of the new silencer/SCR system has already started and it is slated for delivery at the beginning of September.