Meeting international emission-restriction regulations (no matter how strict they become)

1 december 2020

We at Emigreen® are specialized in the design and delivery of the latest technology in Emission reduction. And this is how it works.

Exhaust gas cleaning systems reduce the emissions of NOx (Nitrous Oxide) and Particles (Soot).

As a result of the implementation of our systems, ships will meet international emission restriction regulations even as they are becoming stricter on a regular basis and sometimes influenced by local legislation.

Fact: International maritime regulations restrict the emission of nitric oxide to a maximum of around 2 grams per kWh. Certain projects require even lower NOx emissions. We can handle them without major system changes.

Customized for specific requirements

working exhaust gas cleaning system on this yacht 4

No two engines are the same. As a result, every after-treatment system requires engine-specific settings and specifications. But no matter how different the outcome might be, in essence the working is generally the same in every instance.

The after-treatment housings are designed to function as an exhaust gas silencer. A well-balanced combination demonstrates attenuation comparable to residential grade silencers, with an attenuation of approximately 35 dB(A) and 45 dB(A) for the combined systems. 

The acoustic performance of each housing and silencer can be customised to meet specific requirements.

Active from the get-go

When the engine running signal from the engine is activated, the systems become active and starts monitoring the following engine parameters:

  • Engine load
  • Engine RPM
  • Exhaust gas temperature
  • Pressure inside the systems and total backpressure for the engine

Fact: Once all engine specific parameters have been set, the systems function fully independently and require minimum attention.

The DPF that decimates soot to ash

working exhaust gas cleaning system on this yacht 1

Our DPF-system catches the particles produced by the engine and periodically burns off said particles utilising an automated fuel burner. By increasing the temperature inside the system to a higher level than the engine normally would our systems burn off all the soot and reduce it to ash.

Ashes remaining inside the filter can be removed by the crew at regular or irregular intervals, based on the wishes of the user and the planning of the crew.

The control system monitors mentioned parameters and activates the fuel burner, whenever the parameters reach certain pre-set levels.

Fact: Because of the programming, the maximum allowed back-pressure of the engine will not be exceeded, which assures that the engine will be able to run without restrictions.

Working principle and features of the SCR

The SCR system will start injecting Urea-water (Ad Blue) as soon as the exhaust gas temperatures has reached the required level: the temperature where a chemical reaction between NOx and Urea can take place.

Depending on the load on the engine and the temperature of the exhaust gasses, the SCR is set to inject the exact amount of Urea that is needed to reduce the NOx levels below the required level.

Fact: The higher the NOx exhaust from the engine, the higher the Urea injection will be, which is automatically controlled by the SCR-controller.

Injection rate is pre-set-adjusted based on engine NOx output at a certain load, but is finetuned by a feed-back system fed by information from installed NOx sensors. This is controlled by inhouse developed software.

A certain amount of air will be also injected into the mixing pipe, to increase the mixing properties of the Urea with the Exhaust gasses. The required amount of air is calculated by the SCR-controller and injected via the Air dosing skid (which is included in the system).

Fact: The systems can be connected to the alarm monitoring system, in order to enable the crew to monitor the system from all control locations on board.

Jelle Westerhof is sales manager at Emigreen® and applies our industry-leading solutions to the projects of our clients. Feel free to reach out to Jelle for feedback on this article, for questions and for a free consultation.