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Survey tracks Chinese diesel fuel quality

Analysis of Chinese data for Infineum’s 2014 Winter Diesel Fuel Quality Survey (WDFQS) has just been published. A total of 19 diesel fuel samples were collected from a variety of locations in China, from both urban and rural service stations in the deep winter months, and analysed for 25 different parameters.

The data shows a considerable drop in the average sulphur level compared with previous surveys. However, while some samples, including those from Shanghai and Dalian, have sulphur levels below 10 ppm, one sample collected was found to contain 900 ppm. This huge variation in sulphur content is a real concern, mainly owing to the fact that the performance of certain aftertreatment devices may be compromised if vehicles are fuelled with high sulphur diesel.

Infineum’s China fuels expert, Henry Shi, explains some of the uncertainty surrounding Chinese diesel sulphur levels. ‘In some big cities (for example Shanghai, Beijing and Guangzhou) China 5 diesel is available. However, in other areas China 3 or China 4 quality diesel is still being sold. Another important point to make is that China has implemented two standards for diesel. The first is known as “automobile diesel”, which covers China 3 to China 5 quality fuels and the second is “common diesel”, which contains more than 350 ppm sulphur. The potential for misapplication is a real issue as some service stations sell both grades, mainly because common diesel is far cheaper than automobile diesel.’

China is busy tightening emissions regulations to curb pollution from the more than 240mn vehicles on its roads. China 4 emissions regulations – equivalent to Euro 4 – are being introduced nationwide for diesel vehicles such as light-vans and passenger cars this year and in 2018 China 5 is expected to be the nationwide standard – a measure that significantly cuts NOx and particulate matter and introduces new requirements for particulate number. In addition, China 4 limits, which have been implemented nationwide from January 2015 for heavy-duty diesel vehicles and buses, cut emissions of particulate matter and NOx. These new emissions regulations are driving the introduction of advanced engine and aftertreatment technologies.

Meanwhile, on a global level, the 2012 and 2014 WDFQS reported a stalling of the previously observed downward lubricity trend – something that has been attributed to a backing off in the use of biofuels. However, in China, the reverse is being seen – a continued downward trend and a general flattening of the HFRR (high frequency reciprocating rig) data. In the 2014 samples levels ranged from just over 200 to 439 microns, which means all samples were below the 460 micron local limit. In previous years spikes have been observed at well over 600 microns.

As sulphur emissions limits are tightened hydrotreatment is increasingly used to reduce fuel sulphur levels. This has the knock on effect of lowering the natural lubricity of the fuel. OEMs (original equipment manufacturers) regard lubricity as a key performance criterion because certain parts of the fuel injection equipment depend entirely on the fuel for lubrication, and fuels with poor lubricity can cause catastrophic levels of wear to fuel injection system components. Since no FAME (fatty acid methyl ester) is used in China, refineries rely on lubricity additives to ensure low sulphur fuels are fit for purpose in modern diesel engines. ‘Although some lubricity additive use has been observed in Chinese fuels in the past, this is the first year where, owing to the lower HFFR value, we expect all the samples to contain lubricity improvers,’ notes Infineum.

While operational issues have been associated with the use of some acid-based lubricity additives Infineum research has confirmed the use of proven ester-based additive technology results in trouble-free operation. Some of the CFPP (cold filter plugging point) data also gave cause for concern in that ‘certain samples do not seem to provide the level of cold flow protection that would normally be expected for the winter months’, notes the study. ‘For example, the sample from Beijing had a CFPP of –4°C whereas records show that the minimum daily temperature is –9°C on average in early January, with temperatures at or below –13°C one day in 10. This is in stark contrast to Korea for example. The mean minimum daily temperature in Seoul is also –9°C in January but the national CFPP specification is set at –18°C maximum, with refineries generally meeting the spec with a wide safety margin, ensuring that protection is provided on even the very coldest days.’

‘The investment needed to produce fuels that meet the latest targets will put some Chinese refineries under significant pressure. While the majors are likely to handle the changes fairly easily, smaller outfits may find it difficult to cope, which means variable sulphur fuels could be here for some time to come,’ concludes Infineum.

News Item details


Journal title: Petroleum Review

Keywords: Diesel

Countries: China -

Organisation: Infineum

Subjects: Environmental protection, Environmental Health, Environmental pollution, Air quality, Environmental research

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