Stabilized triglycerides By Green Oleo

Vegetable oils based fluids are a sustainable alternative to the mineral-based products. Characterized by high viscosity index, good behavior at low temperature, high flash point, high lubricity, resistance to oxidation, renewability and biodegradability, triglycerides have become a widely used option for a number of applications. Metal working, transformers cooling, hydraulic circuits service, chainsaws lubrication are successful examples of possible use of STG (Stabilized TriGlycerides). High oleic triglycerides and STG have widened the number of applications you can satisfy using natural oils. Their use in the food industry help to reduce hydrocarbon contamination due to mineral oils, in all applications they contribute to circular economy and to the reduction of environment contamination. High oleic sunflower oils have been gaining more and more room in the lubricant field but the focus has to be on the composition rather than the source of the natural oil, today more than before considering Ukraine’s position as one of the world’s largest supplier of sunflower seeds.

STG based Hydraulic fluids – Bench test

Many studies have been carried out to investigate the performances of hydraulic fluids developed from oil crops, the key point is the fatty acids composition with particular attention to the amount of linoleic and linolenic acids because of their poly-unsaturated bonds. Thanks to natural polarity, lubricity, high flash point, pour point, viscosity index, and thermal stability of the molecules of STGs, only an anti-oxidant additive is needed in order to reach the standard TMPO ester based lubricants performance.

A bench test, capable of performing severe hydraulic cycles with the aim of accelerating the ageing of the lubricant has produced the results we report hereafter. The basic idea is to accelerate the ageing of the tested fluid by applying high controlled levels of mechanical, hydraulic, and thermal stress.

ParameterUnit of M.Value
Fluid volumelitre    25
Max PressureMPa    40
Min PressureMPa       0.15
Max Temperature°C  100
Min Temperature°C    58
Pump rpmmin-11800
FlowrateLitre min-1       5.3
Hydraulic PowerKW       4.18

Each work cycle at the bench requires 20 l of oil, as to the work cycle duration, if the global energy developed (hydraulic work and thermal energy) is referred to the fluid volume unit (specific energy, kWh dm−3), it has been assessed that the specific energy developed in a 150 h work cycle under the conditions reported in the table would correspond to the average of a hydraulic system of a medium power tractor with an oil volume of 80–100 l. The authors decided to extend as much as possible the test duration, until the occurrence of significant modifications in technical performance and/or in chemical-physical parameters.

he test lasted 530 h. It was suspended after 66 days of work (average time of work: 8 h day−1) when the oil volume in the bench as a consequence of the many sample takings became too low to ensure its correct working.

Lubricant characteristics before starting the test and at end time (530 h)

ParameterUnit of M.            Value
  T 0hT 530h
Viscosity @ 40°cSt    39,9    40,3
Viscosity @ 100°cSt      8,54       8,60
Viscosity Index 199  199
TANmgKOH/g      0,32       0,48

The lubricant at the end of the test still satisfies the minimum performance required, the amount of residual anti-oxidant is 40% of the initial, which was a standard quantity. No issues have been detected on mechanical parts examined at the end of the test.

An interesting  point is the end of life of lubricants; from a circular economy perspective, it is necessary to think about the possible uses of the exhausted products. Using STG, different solutions can be hypothesized: Fatty acids production, Bio diesel production, bio gas production, energy production via different technologies.

About Green Oleo
Green Oleo has almost 100 years of experience in the production of fatty acids and glycerin. Produces fatty acids from a wide range of triglycerides, esters from its own fatty acids and other sources. Green Oleo is building a new approach to oleochemicals starting from renewable sources.

Green Oleo are exhibiting at Lubricant Expo on stand 337.