Technology Circular economy

Chinese energy opts for EST

 By Luca Longo
Circular economy

Besides Total, the chinese Sinopec is also set to adopt Eni’s “EST” technology…

Pechino is taking steps to decrease the environmental impact of its own energy industry, thanks also to Eni’s technology. At Sinopec’s refinery in Maoming, Guangdong, a plant will be built based on the so called “EST” technology. EST stands for “Eni Slurry Technology” and will be used by the Chinese to refine the heavier residues from oil production and turn them into lighter, more valuable products, such as diesel and petrol. The crude oil extracted from the subsoil is a mixture of numerous organic molecules, mainly consisting of carbon and hydrogen: the hydrocarbons.  These molecules can vary in size.  The lightest is methane, consisting of just one carbon atom, together with four hydrogens but let’s concentrate ourselves on carbons alone, which remain in a gaseous state and is the main component of natural gas, followed by ethane (slightly less volatile than methane and consisting of two carbon atoms), propane and butane (with three and four carbons) and pentane, with five carbon atoms, which is the first of the hydrocarbons that stays liquid at room temperature.
Heavier molecules consist of increasingly longer carbon atom chains and when we reach a number of twenty (or more ) carbons we obtain solids which  at room temperature remain in the same solid state and have to be heated up (in increasing temperatures) to bring them to fluid state.
To use crude oil, component molecules need to be separated, based on their different length, exploiting their different boiling points.
Refineries serve this purpose: they are huge distillation plants where the crude oil produced from oil wells is injected into a large vertical column.  The column is filled with porous materials that enable the mix of hydrocarbons to move up and down.  By heating the base of the column, a part of the crude changes its state to vapour, but going up, gets into contact with colder parts of the column so it condenses and the liquid flows back downwards, starting the cycle up again.

chinese-energy-industry-opts-eni-technology
Sinopec Headquarters in Pechino (WhisperToMe, Wikimedia)

Molecules of the same size (at boiling temperature) gather all in the column at the same height: the lighter molecules at the top and the heavier ones at the bottom.  At this stage, the various separate fluids can be collected at different heights of the column.  Starting from the top, gas, then petrols, kerosene, diesel fuel, fuel oils, bitumens and asphalts will all come out. At the bottom of the column there will be molecules so heavy that they cannot be dissolved or evaporated.  These can only be burnt, perhaps to heat the same refining column.  Unfortunately, fractions with a high sulphur and heavy metal content also settle at the bottom and these are significant environmental polluters.
This is why research has tried to explore methods to turn these refining residues into lighter products with a higher commercial value.  In Italy, after 20 years of scientific research – “EST” technology was created. With molybdenum-based, nano-dispersed catalysers, which can be recovered and recycled, hydrogenation reactions can be generated with a remarkably high conversion rate. In other words, with EST, longer carbon atom chains can be cracked and turned into other lighter, more valuable chains, with a yield of more than 95% compared to a maximum 70% attained by competing industrial technologies. This means the “bottom of the barrel” can be recycled , i.e. all the substances that cannot be refined in the distillation columns, plus all the high-quality liquid products which EST can produce have a low content of sulphur, nitrogen, heavy metals and other contaminants. EST can also lower the sulphur content in maritime fuels, offering the best technical solution in line with new International Maritime Organization (IMO) regulations. The new Sinopec plant implementing “EST” technology will have a capacity to handle up to 46 thousand barrels a day starting from 2020, and represents a further application of the plants adopting the same technology at Eni’s refinery in Sannazzaro de’ Burgondi (Pavia) in addition to that already bought by Total in 2015.

READ MORE: China’s natural gas opportunity by Peter Ward

about the author
Luca Longo