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Retorting Enefit140

Eesti Energia's oil and gas company uses the two Enefit140 units to refine around 1.6 million tons of oil shale per year and produce more than one million barrels of various shale oil fractions. About 50 per cent of the products are exported and used as components in liquid fuel. Local consumers mostly use shale oil in boiler plants and smaller power plants to produce heat and power. It is also used in agriculture and road construction.

In addition to its oil production units, the factory also has an accredited chemistry laboratory that can do any sample tests and analyses needed. This allows the proper functioning of the machinery and the quality of the production to be assessed on-site, as well as closer adherence to environmental, health and safety requirements.

Enefit Shale Oil Production (thousand barrels)

Enefit Shale Oil Production (thousand barrels)

Enefit140 process

Enefit140 process

Drying
The flow of flue gas directed from the lift-pipe combustor to the dryer dries and preheats the wet oil shale.

Combustion
The waste product of the retort process – a mixture of semi-coke and the heat carrier – is ignited in the lift-pipe combustor. The energy from this combustion is used to heat the solid waste, the ash, before it is redirected into the process.

Thermal decomposition
Ash is used as a heat carrier. Oil shale and the heat carrier are mixed in a horizontal rotating retort, causing thermal decomposition of oil shale and release of a vapor-gas mixture.

Solid residue – semi-coke – is separated and fed to the combustion unit. The vapor gas mixture is cleansed of dust and proceeds to the condensation section.

The initial design of the plant called UTT3000 did not work, producing oil at only 1% of its design capacity in the first year of operation. Approximately 70% of the initial design has been reworked to get the unit up and running; the redesigned unit is now called the Enefit140. The key area of improvement was the increase in the units' online time, which had only hovered around 45% prior to improvement. Now it is close to 80% and we have thus exceeded the initial as-built capacity of the plant, which was 75%.