Maximising diesel fuel yields

The global fuels market is changing as stringent fuel economy standards contribute to a levelling off or decline in gasoline consumption, while diesel fuel use is on the increase in all regions – most notably in Asia Pacific. 

Looking at future global trends, we can expect to see a significant increase in the demand for middle distillates – with diesel alone growing by 10 million barrels per day by 2040. This demand is driven not only by an increase in the number of diesel commercial and passenger vehicles on our roads, but also by the growing interest in the use of middle distillate fuels in the marine world as sulphur emission limits tighten.

US refiners are expected to focus on shifting their production from gasoline to distillate fuels to meet growing domestic and global demand for diesel, and exports of finished products to international markets will continue to grow steadily in the coming years.

These demand trends, combined with tight margins, are driving refiners to look for ways to maximise diesel production without increasing costs and without the need to invest in expensive capital projects.

Maximising diesel production

In the past, US refiners have focused on the production of gasoline, while in Europe most refiners have concentrated on diesel production – with refinery hardware and operation optimised to maximise these outputs. However, in the current climate, as US refiners put more focus on diesel fuel production, it is hardly surprising that they are looking to Europe to see how these refineries maximise diesel throughput and profits. 

A major, and sometimes overlooked, difference between the US and other major markets is the specification used for moving middle distillate products through pipelines.

In the US this is driven by cloud point and pour point, while elsewhere an operability specification has been adopted for the movement and sale of diesel fuel.

The ASTM D975 standard specification for diesel fuel provides low temperature operability guidance and, along with cloud point and Low-Temperature Flow Tests, CFPP is included as a key measurement of diesel fuel operability performance. While, until now, cloud point has been the standard metric in the US, there is no industry diesel fuel specification forcing its use. Refiners do not have to employ cloud point as their release specification, except to meet the loading specifications of the various pipeline companies.

To meet lower cloud point specifications, refiners either need to operate at lower cut-points than desired, or blend with #1 ultra low sulphur diesel – which has been common practice in the US. However this not only lowers the cetane number and the energy content of the fuel, but also reduces the amount of higher value jet fuel available to the market.

Switching to CFPP

The most common operability specification in Europe uses the cold filter plugging point or CFPP test, which is included in the EN590 European Standard for diesel fuel.

The CFPP test procedure was developed almost 50 years ago, as an alternate method to the cloud point test, for predicting the low temperature operability of a diesel fuel in a vehicle engine.  

This, automated, bench-scale test is quick to run and correlates the actual field operability of diesel vehicles to the filtration performance of diesel fuel at low temperature in a lab environment.

An operability specification has the potential to revolutionise the way in which US refineries optimise their profitability in the future.

Adopting CFPP as the low temperature operability specification for the release of diesel fuel in the US would allow refiners to increase the cloud point of their diesel fuel, and to use cold flow additives to reduce CFPP ensuring consistent low temperature operability performance. This approach would enable blenders at the refineries to put more lower value, heavy fuel streams into the diesel pool.  However, adopting CFPP does not mean abandoning the cloud point specification altogether because the delta between the two can easily be adjusted to meet specific refinery targets.

Based on our testing experience, we estimate that - while extremely variable and fuel dependent - allowing the diesel pool cloud point to rise by 5°C would allow up to 10% of heavy fuel streams to be released into the diesel pool. 

Adopting CFPP as the low temperature operability specification could create an additional 3.5 billion dollars revenue for the refining industry. 

How do we come up with that figure? By taking the 5% cloud point elevation as a realistic basis, we were able to calculate the net value of the fuel upgraded to the diesel fuel over a four month period – clearly even more lucrative scenarios exist. 

Cloud point elevation is a cost effective way to increase refinery profitability Enlarge view

With this amount of potential gain, CFPP giveaway is clearly preferable to cloud point giveaway. Missing cloud point even by one degree can be very expensive versus the cost of additional additive treatment, which can be written off against achieving the best fuel optimisation.

Each refinery or terminal will be affected in different ways by winter blending challenges and changing demand patterns. It is not always immediately apparent what the implications might be in terms of fuel characteristics or additive requirements and sometimes even a small change in operation can have a huge effect on additive needs. 

Working closely with individual fuel refiners and suppliers and applying the experience gained over many years with our customers in Europe, ensures the delivery of cost effective additive solutions, which can optimise the production of harms free diesel fuel for US refiners.

As the demand for light products increases, cold flow additives will become an increasingly important tool to help US refiners to correct the middle distillate shortfall, maintain vehicle operability and handle the growing number of difficult-to-treat fuels.

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