The game-changing legislation which came into force on 1st January 2015 – is the use of 0.1% sulphur fuels in the ECAs. The obvious choice for the ship managers was to change-over to a low sulphur distillate fuel. However, the market witnessed new fuel types which are called as the hybrid fuels in general – where they are neither residual nor distillate fuel. They fall in-between these two segments, which created a lot of confusion when ordering a fuel.
Ship Managers frequently looked-up to Viswa Lab for guidance on safely using such hybrid fuels. Viswa Lab, till date, emphasizes that these hybrid fuel parameters, though within the ISO specified limits, does not fall under ISO specifications, unless the fuel supplier clearly specifies the grade as per ISO 8217. To understand this further, we approached Mr. Murali, Vice-President, Global Bunker Quantity Survey, Viswa Lab, for his comments.
“Not everything that burns can be considered as a marine fuel. When tested, such fuel parameters may fall within the ISO 8217 specified limits. This alone does not mean that the fuel is as per ISO 8217 specifications”, said Mr. Murali, who is an ex-Marine Chief Engineer and an expert in bunker quantity survey.
The fuel suppliers have to clearly state under which grade the fuel falls under ISO 8217 specifications. In general, the shipping industry is happy with the quality of the hybrid fuels though they have some inherent compatibility/stability issues.
Based on the feedback, it is to be emphasized that the ship managers do not have much of a control over the fuel being supplied by the charterers. Thus, there has been many ambiguities in handling the ultra low sulphur hybrid fuels on board the ships. Many of the ship managers are left with questions unanswered especially when it comes to handling, storage, and purification of the hybrid fuels.
Ideally, the fuel supplier should provide the information along with all specific fuel characteristics for safely using the fuel in the main and auxiliary engines. However, this is, as usual, not the case with the suppliers.
Many ship managers, who already have plate full of problems to deal with are posed with one more – how to store/heat/purify the hybrid fuels!
We have digged deep into this topic – which we found answers working close with Viswa Lab and Alfa Laval. Don’t be surprised when someone talks about the NEFs. They are nothing but an acronym for New ECA Fuels.
This part of write-up will feature more about heating/storing and handling the NEFs or the Hybrid fuels (ULSFO).
1. Do I have to heat the hybrid fuels? Since the viscosity is low – I can close the steam and save fuel burnt in the boiler.
Answer: Believing that heating is not necessary with gas oil, some operators considered blocking off the tank heating in order to prevent water from leaking heater coils from entering the tanks and to save money through reduced heating costs. However, this is a misunderstanding that can prove expensive in the end. Heating is still needed for gas oil due to the increasing amount of wax it contains. Moreover, some of the hybrid fuels on the market must be handled in the same way as HFO.
2. What Temperature should I store MGO/LSMGO in the tanks during winter or cold climate zones?
Answer: In general, keep the MGO/MDO in the storage tanks at 30°C, especially during winter conditions, to prevent wax formation where the fuel meets outside temperatures. Additionally, it is recommended to carry out a simple test for cloud point or CFPP or alternatively contact Viswa Lab for further recommendations.
3. What temperature should I purify the MGO/MDO in winters?
Answer: If a separator is used to clean the MGO/MDO, a preheater should be used to raise the temperature to 40–45°C. This will ensure that the wax is not removed in the separator. Once again, these are general recommendations. Other factors to be considered are the viscosity of the fuel and other test parameters like pour point, cloud point etc. For hybrid fuels or ULSFOs, the separation temperature is usually determined by the viscosity of the fuels used. If a hybrid fuel is used, Viswa Lab recommends to store it at a correct temperature for that fuel, which is usually 10°C above its pour point.
Other recommendations:
- Keep the tanks as full as possible when storing fuel for longer periods, because there will always be some condensation in the tanks. The less area there is for water to gather, the less water will enter the oil.
- If there is no possibility of drainage, Alfa Laval recommends installing a small separator to remove the water and other contaminants if any.
- The hybrid fuels or the ULSFO are on the verge being unstable due to the production method used in the refinery. This means if the NEFs are mixed with water or other oils, normal ECA fuels, they will most likely produce a lot of sludge due to instability. It is, therefore, paramount that ULSFOs or the hybrid fuels are tested before being mixed with any other oils or, at the very least, a spot sample is taken to see if the two oils are compatible. You can consider equipping every ship with Viswa Lab’s on board compatibility/stability test kit – such that the ship’s staff can test the fuels before any attempt is made to co-mingle the fuels.
- At times, even mixing a hybrid fuel with another can cause stability issues.
- For the greatest safety, run all fuel through a separator to ensure the removal of all contaminants – including water.
- If the fuel is not clear and bright, it should absolutely be cleaned in a separator before consumption. Some fuels are dyed black, and there is most likely a reason for it. These fuels may contain even more contamination, e.g. cat fines, says Alfa Laval.
- The separator must be independent of the usual HFO separation system, due to the higher sulphur content of the HFO.
- Due to wax content, a heater should ideally be used to heat the oil to 40–45°C. Make sure that the viscosity at the engine inlet does not fall below 2 cSt as per engine maker’s guidelines.
While we can keep writing stacks of recommendations, the above are the most important points to consider when handling the ECA fuels. In the next write-up, we will cover an exclusive content on purification of hybrid or ECA fuels.
We thank Alfa Laval and Viswa Lab for providing valuable information and sharing operational details with MFAME.
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