Very Low Sulphur Fuel Oil stability solutions
11 October 2021
15 September 2021
To meet IMO 2020 sulphur specifications, low sulphur cutter stocks have been introduced into the heavy fuel oil. This may result in waxing issues and operability challenges as many of the cutter stocks are highly paraffinic.
Infineum has been investigating this issue over the past year. This video highlights some of the progress we have made in this area.
Hello, my name is James Challis. And I'm a Fuels Technologist for Infineum UK. I'm currently leading a project, which is looking at wax management additives for marine fuels. Today I'm going to talk to you about my project, what we've learned and some important information about marine fuels. As of January 1st 2020, there was a big specification change for marine fuels, namely, the sulphur levels were reduced, affecting both residual and distillate grades. So the protection from a wax management perspective for these fuels is the cold flow specifications. And for these fuels, it's pour point. For the residual based fuels, there's a pour point specification of +30 degrees. For the distillate grade fuels, they have summer and winter specs for pour point. And as of 2017, there was a cloud point, and CFPP reported spec added. Before January 1st 2020, the pour point specification served the industry well, it prevented any sort of quality issues or waxing problems in the fuels. Since January 2020, there has been a significant change in the makeup of these fuels. To meet the sulphur specifications, there has been an introduction of many new cutter stocks, which helped reach the sulphur limits. Majority of these cutter stocks are highly paraffinic. And that means that you're introducing a lot more of waxy material into your fuels. That obviously is going to have an effect on the cold flow properties of your fuel. Infineum has been looking into this over the past year or so and we have seen trends between the pour point and the viscosity of these marine fuels. What you're seeing now is a graph that shows the pour points and the viscosities of various sulphur grade fuels. You'll see that the new very low sulphur fuel oils typically have a far greater pour point than their high sulphur counterparts. In addition to this, you'll notice that there's a much greater viscosity range, and that predominantly the viscosities of these fuels are far lower. This is going to introduce major operability changes and potentially problems when using these fuels. So, how can Infineum help? Over the last year or so Infineum have been looking into these fuels, and we've been developing fuel maps. And what fuel maps do is they show us the fuel effects and the characteristics that influence the waxing behaviours of these fuels. The map you're seeing now uses physical characteristics to highlight additive preference, and also typical additive performance in these fuels. So how you manage the wax. In addition to these fuel maps, we've also been investigating the difference between the pour point of these fuels and the temperature of which the wax precipitates, commonly known as the Wax Appearance Temperature. What we have seen is that in these fuels, the difference between those two temperatures can be very vast, up to sort of 40, 50, 60 even 70 degrees. And the problem with this is that the fuel specification for these fuels of +30 degrees will no longer protect your fuel if wax is coming out at far higher temperatures. To provide protection against this, Infineum has been developing operability rigs. These rigs are test equipment that replicates some typical environments that you will have onboard a ship, on a vessel. We've been working with shipping companies and ship users to ensure that they are representative of real environments that you'll see. And what you're about to see now is something that we've called the wax settling rig. It's essentially a rig that tries to mimic the storage conditions on a ship, the fuel tanks or as a storage tank. And in this in this video here we have used a high cloud point marine gas oil to show the benefits of using additive. You'll see that there's an untreated tank and a treated tank. And in the treated tank, you'll see that the additive is having an effect on the wax that's coming out of the fuel at a lower temperature. Because of that you're getting a less gel like wax, more fluffy movable wax. Which means that when you try to pump the fuel out of the tank at the end of the test, you are left with far less wax and you can pump more fuel out of your tank, which obviously has benefits in the fuel. So hopefully this is a clear demonstration of the visual problems that wax can create in these fuels, and also how Infineum can help and Infineum additives can alleviate some of these problems that you may see. If you'd like any more information about this, please contact your local Infineum sales representative or contact Infineum UK. Thank you.