pH simulation of marine scrubber discharge
To meet the marine scrubber discharge regulations FORCE Technology offers 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. Exhaust gas cleaning systems also known as scrubbers, which clean out the emissions before releasing the exhaust gas to the atmosphere.
At the same time, 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 pH6.5 at 4 m from the overboard discharge point of the ship. To document compliance FORCE Technology has developed a CFD model (computational fluid dynamics) that simulates the pH value in the seawater in a 4 m radius around the wastewater discharge.
Fluid mechanics and chemical models are combined and included in the CFD model. This gives a clear indication that the scrubber unit can in fact discharge wastewater with lower pH than expected because of the mixing of the seawater around the discharge hole, hence the lowest possible pH value for discharge water is found.
This can result in a decreased OPEX for the scrubber system.
If the scrubber supplier has a predetermined pH outlet value our CFD model can calculate the minimum flow needed to obtain the wanted pH value.
Approved by several classification societiesThe 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
As FORCE Technology holds 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 this, 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. These inserts are known to cause risk of corrosion issues at the outlet.
Using our CFD model, it is no longer necessary to use these inserts, the flow and pipe conditions are optimised to reach compliance.
Visual presentation of CFD results
The CFD model gives a visual presentation of the results and it gives a fast and clear picture of the obtainable 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 or the shipping company.
By using our CFD model, it is often possible to simplify the pipe arrangement and we can design the pipeline to ensure discharge of a lower pH value or optimise the flowrate.