The 2020 IMO global 0.50 percent fuel Sulphur Technical Note:
In less than a week time, From 1st January 2020, the maximum permissible global Sulphur content of marine fuels is going to be reduced from
3.5 % to 0.5% according to MARPOL Annex VI. Ships operating outside
Emission Control Areas (ECAs) will have three options to achieve compliance:
- By the use of exhaust gas abatement technology (‘scrubbers’), or
- By burning a fuel with maximum Sulphur content of 0.50%mass, or
- By burning LNG. To meet continuing legislation inside ECAs.
To meet continuing legislation inside ECAs, ships will either have to use scrubbers or burn fuel with maximum Sulphur content of 0.10%mass or use LNG.
Here is a short technical note with regards to IMO 2020 Sulphur requirements based on available resources from prominent global maritime stakeholders. Technical circular s from MAN Energy Solution, Winterthur Gas and Diesel, BP and others briefly highlighted the upcoming scenario.
There are multiple challenges in dealing with Very Low Sulphur Fuel Oil that comply with current IMO regulations. Some key factors are mentioned below:
- VLSFO must be compliant with ISO 8217:2017 standard. VLSFO likely to have similar properties to ULSFO(Ultra Low Sulphur Fuel Oil).
- Considering Origin and difference in Distillery process, few important parameters requires particular attention to combat. These are:
- Compatibility and/or stability
- Viscosity
- Cold flow properties
- Calculated Carbon Aromaticity Index (CCAI)
- Catalytic fines concentration
- Aromatic or paraffinic nature of VLSFO can lead to compatibility problems. If Aromatic Fuel mixed with Paraffinic Fuel on board, initially it may be show stable condition but after prolonged time in tank it may cause sludge formation due to a change in solubility properties.
- High fractions of paraffinic components in VLSFO may lead to wax formation for prolonged exposure in cold condition. Before Bunkering, make sure the fuel cold flow properties comply with the fuel system design and the planned ship routing. Cold flow properties of a fuel are frequently defined by the pour point (PP). Fuel should be heated sufficiently to be able to flow freely and be homogeneous in order to avoid filter blocking. It is recommended to keep the temperature between 30-40°C to minimise the risk of wax crystallization. Maintain the fuel at 15°C above the pour point.
- Broad range of viscosity of VLSFO even within the same grade is a challenge to combat. Low viscosity levels similar to DM of some VLSFO requires particular attention to handle. In that case all the procedures for typical HFO treatment must be applied.If the viscosity is lower than 2 cSt, the fuel injection may be compromised. In such case engine start test is recommended on very low viscosity fuel to verify whether the pumps are sufficiently unworn to be able to build up sufficiently high pressure. Carry out this test before entering high-risk areas e.g. ports and other congested areas or at least every 6 months. If viscosity of the fuel gets too high, it will lower the effective injection pressure for the ME engines, which may lead to slower injection and a lower degree of atomisation of the fuel. mechanically driven fuel pumps, cams and camshaft may experience difficulties in handling the thick fuel.
- level of cat fines in VLSFO may vary depending on the refinery streams. It is recommended to maintain fuel purification system at high efficiency level.Cat fines are small, very hard particles which can wear the engine fast.
- During Bunker requisition order as per ISO 8217:2017 standards. Relevant properties of the fuel should be requested at bunkering. Make sure viscosity, pour point, cat fines concentration as well as total sediment potential are within the limits given by this standard. Confirm the level of properties by sending fuel samples to accredited laboratory for analysis.
- A fuel management plan should be drafted confirming detailed procedures of all steps prior to bunkering and until the fuel is used.
- Avoid Deliberate blending of these different fuels in the storage, settling or service tanks, each newly bunkered fuel batch should be stored in a separate storage tank.
- Situation may arise that Due to ship operators pressure, supplied oil may have to use if it is within slupher limit. In that case carry out compatibility test of oil. For compatibility test follow extended version of ASTM D4740 on which the only acceptable cleanliness level is Rating 1. Please note that this type test only provides an indication of the compatibility of the fuels. In some cases highly paraffinic/waxy fuels might yield a false negative result during the compatibility test. If fuel is blended in tank in any case and it pass compatibility checking, still the fuel should be consumed as soon as possible as there is high chance of sludge formation after storage of few days.
- It is very important to keep close eye on performance while consuming this oil. Adjust purifier gravity disc basis it’s density. If the gravity disc is not suitable for the fuel in use, the oil-water interface in the separator will not be correct, and the fuel will not be cleaned. Water may be led with the fuel to the engine or the fuel will be led to the drain with the water. Latest purifiers are self adjusting. Ensure cat fines to below the specified maximum engine inlet levels by maintaining purifier at high efficiency level with low throughput and high temperature. If excess sludge is observed in purifier, immediately switch to distillate grade and notify office.
- Ensure proper operation of Viscosity meter and Adjust the temperature accordingly to reach the specified engine inlet viscosity. When new batch of fuel is going to be used, ensure that the quantity of previous fuel remaining is kept to an absolute minimum. Possible sludge accumulation should be monitored by observing drains regularly.
- To protect combustion chamber components against corrosion, the base number of the Cylinder lubricant must be suitable. Study engine manufacturers Base Number vs. Fuel Sulphur content graph for selection of base number. Send piston underside drain oil sampling for analysis regularly and interpret the results. Check piston and piston ring conditions through scavenge port inspections regularly.
- The best way to combat 2020 Sulphur cap operating conditions is through Optimum Engine design. Optimised temperature profiles of Cylinder liner resist cold corrosion. Fully plateau honed cylinder liner running surface reduces running in time and friction. Chromium ceramic coated piston ring pack provides
excellent seal between combustion chamber and piston underside and reduces running in period as well as facilitate long overhaul intervals. Pulse Jet lubricating system with patented lubricating oil grooves ensures excellent oil distribution to prevent uneven component wear.
- ISO plans to release a publicly available specification (ISO/PAS 23263) and CIMAC WG-7 “Fuels” intends to publish its own guidelines. Follow their guidelines for better understanding.
17.Fuel Oil Non-Availability Reports (FONARs) sent to the ship’s flag State and all the supporting documents (to be retained on board for inspection for at least 12 months). It should be noted that a FONAR is required to be sent to the ship’s flag State and the next arrival port. FONAR can be sent till 1st March 2020, after that total carriage ban will be enforced for non-compliant fuel.
To read more, download the IMO circular pdf file by clicking the below links:
http://www.imo.org/en/OurWork/Environment/PollutionPrevention/Documents/MEPC.1-Circ.878.pdf
http://www.imo.org/en/MediaCentre/HotTopics/GHG/Documents/2020%20sulphur%20limit%20FAQ%202019.pdf
Author:
MarEngr. Abul Basar, Surveyor and Examiner