Glycerolysis

Glycerolysis is a chemical process that converts free fatty acids (FFAs) contained in low-grade feedstocks into glycerides, making them usable for biodiesel production. Glycerolysis is an increasingly essential pretreatment in the economics of biofuel production from low-quality raw materials.

To fully understand the importance of glycerolysis, it is necessary to take a step back and remember that the biggest difference in biodiesel production is local legislation. In the European Union, vehicles with internal combustion engines must be equipped with a catalytic muffler. This device cannot tolerate biodiesel combustion residues, which must be not exceed 7% in fuels, in order to be used without damaging the engine. Unfortunately, however, the European Union itself has mandated that at least 10% of the fuel from renewable sources must be present in the diesel blend used by vehicles in Member States.

The solution is to use biodiesel produced from used oils unsuitable for human consumption, as in this case the so-called double counting system applies. This is a legislative mechanism that doubles the energy value of this sustainable biodiesel, increasing the power of that 7% to 14%, thus bringing the blend within legal parameters.

The products  of glycerolysis can be fed into conventional transesterification units without any modification, making them suitable for high-acidity feedstocks.

TECHNOLOGY ADVANTAGES

Glycerolysis, by optimising biodiesel production, offers at least three specific advantages:

• Greater process sustainability, thanks to the reduction of production waste, which, instead of representing a cost, becomes a resource to be utilised;
• Economic maximization, optimisation of raw material exploitation and obtaining products with a high market value;
• Easier compliance, thanks to the possibility of exploiting the double counting system, which allows easier access to the Western market.

Specifically, the glycerolysis process occurs as follows: high-acidity raw materials such as soapstock fatty acids, FAD or high-acidity oils are reacted at high temperature for several hours with an excess of glycerine to convert the fatty acids into a mixture of mono-, di- and triglycerides.

The conversion is an equilibrium reaction, therefore the unit operates under vacuum to immediately evaporate the water formed in the reaction and thus improve conversion.

The plant consists of cascade reactors, each equipped with recirculation and heat exchanger.

High capacity plants, especially in the Far East, also include a final stripper to remove most of the residual acidity (and part of the monoglycerides), which are recycled in the esterification section.

The long residence time at high temperatures makes the formation of certain polymers inevitable, especially with polyunsaturated raw materials such as soybean or sunflower oil.

The polymerisation reaction increases significantly with increasing temperature; it doubles with every 10 °C increase, while it is linear with residence time.

FURTHER ADVANTAGES OF CMB TECHNOLOGY

In a process such as glycerolysis, it is essential to combine optimised engineering with seamless process management, both in terms of phases and timing.

CMB’s end-to-end management allows to benefit from the best solution for the specific needs, from the initial briefing to turnkey delivery of the production plant, supporting its Clients step by step, to achieve the exact result they desire.

CMB design provides for a lesser critical operating reaction conditions to minimise polymers formation; this requires a longer residence time, but the overall result is significantly less polymer formation, despite some increase in the initial investment.

This design approach used by CMB is really beneficial to the Client, as it offers a faster return of investment (ROI) than any other type of reactor built for the same purpose.

As with all CMB plants, great attention is paid to obtain the maximum heat recovery with high-surface-area heat exchangers, and this, combined with lower operating temperatures, makes the CMB plant extremely energy efficient.

In summary, a CMB glycerolysis plant allows Clients to achieve:

• Optimisation of production costs, thanks to design and engineering that reduce energy waste and maximise productivity;
• Maximum yield of feedstock by-products, regardless of their initial quality, thanks to the possibility of designing customised processes, always providing Clients with a high-performance solutions;
• High quality of final products, as CMB’s technologists’ in-depth knowledge of production processes allows to obtain a final product with the best characteristics in terms of purity and stability;

So, take the opportunity to contact a CMB professional consultant and get all the information you need. Write now to: info@cmb.it and our experts will show you a complete range of solutions ready to boost your business.

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