To meet the marine scrubber discharge regulations we offer a quick and flexible model to document compliance, with several projects approved by range of classification societies.

New marine emission regulations from 2020

As of 1 January 2020, IMO has set a global limit for sulphur of 0.5% in marine fuel used on board ships to reduce the amount of sulphur oxide (SOX) emitted from ships.

To meet the SOX emission requirements, ships may either use fuel with less sulphur or use approved methods for flue gas cleaning. This could be exhaust gas cleaning systems also known as scrubbers, which clean out the emissions before releasing the exhaust gas to the atmosphere. The scrubber suppliers or shipping company must document that the wash water discharge does not harm the marine environment.

Includes both physical and chemical conditions

According to MEPC, the discharge wastewater must have a pH-value of no less than pH 6.5 at 4 m from the overboard discharge point of the ship. To document compliance we has developed a CFD model (computational fluid dynamics) that simulates the pH value in the seawater in a 4 m radius from the wastewater discharge.

Fluid mechanic and chemical models are combined and included in the CFD model. This gives a clear indication, if the scrubber unit can in fact discharge wastewater with lower pH than expected because of the mixing of the seawater around the discharge hole. Hereby the lowest possible pH value for discharge water is found. This can result in a decreased OPEX for the scrubber system.

pH simulation of marine scrubber discharge

Approved by several classification societies

The methods used in the CFD model and its documentation have already been approved by several classification societies for documentation of compliance with MEPC.259(68). 

Access to hull geometry database

We hold many years of experience in the maritime business we have access to databases with a vast variety of hull geometries. This is very useful when documenting the compliance of the scrubber, together with the discharge pipe arrangement.

For situations with very complicated discharge pipe arrangements the model can help to optimise piping, which could lead to a decreased CAPEX for the scrubber system. Various examples of inserts used in the discharge outlet to obtain the necessary flow conditions to comply with the coming pH regulation have been seen and testet. These can be optimised to obtain compliancy with a given pH at a certain pressure drop. 

Visual presentation of CFD results

With the CFD model the results are presented visually and it gives a fast and clear picture of the obtained results and how to comply with the regulations. It is a powerful tool when communicating with the classification companies and getting to know the details of discharge conditions.

Possibility of simplifying pipe arrangement

When installing the scrubber unit, the pipe arrangement is either designed by the shipyard, scrubber supplier or the shipping company. By using our CFD model, it is possible to simplify the pipe arrangement, which can lead to lower CAPEX of the scrubber system. 

Quick and flexible model

The method of using CFD simulation offers a quick solution, suited for the specific discharge layout. The report may be used as documentation in communicating with the classification companies in preparation for an approval of the scrubber unit design and discharge.