Fatty acids fractional and total distillation

An important step in the fatty acids production process is the distillation, which is required to separate heavy boiling impurities and colouring agents.

The main distillation tower may be preceded by one to three fractional distillation towers, in case fatty acids are to be separated into individual components.

The fractionation process is based on the different vapour pressures and thus  separates fatty acids of different chain lengths while the split of saturated from unsaturated fatty acids is carried out by crystallisation.

The raw materials for fractional distillation are almost exclusively palm kernel fatty acids or  –  coconut  fatty acids (the latter to a lesser extent due to their cost and availability), as only these two oils include all fatty acids from 6 to 18 atoms of carbons in their composition. All other oils (with a few exceptions for the heavier fatty acids) contain almost exclusively fatty acids with 16 and 18 carbon atoms. Their use is therefore limited to special cases, such as soyabean fatty acids for the paint industry, where an initial tower removes the C16 cut (which is saturated) to have a highly unsaturated product with drying capabilities.

Fractionated fatty acids have various industrial applications:  for instance, the cut C8/C10 is used for the production of infant food, the cut C12/C14 is converted into fatty alcohols for the detergent industry, C16 fatty acids are used in cosmetics and pharmaceutical industries.

High-capacity fractional distillation units are mainly located in the Far East due to the local availability of the raw materials.

TECHNOLOGY ADVANTAGES

The fatty acids distillation, and in particular the fatty acid fractional distillation technology, was greatly improved in the 1980s with the use of structured packings.

The separation of fatty acids into high purity products requires a large number of theoretical stages and this could not be achieved with random packing or trays, as their pressure drop would have made the bottom temperature too high, leading to polymerization or cracking problems.

The introduction of structured packings, capable of providing more than 2 theoretical stage per meter with a drastic reduction in pressure drops per meter, solved this problem by allowing the production of fatty acids with concentration above 99 %  with limited bottom temperatures.

Fatty acids, especially unsaturated ones, tend to oxidise with consequent colour degradation, so they must be kept at temperatures as low as economically possible.

The reference to economic considerations is due to the fact that low temperature means low pressure (fatty acids distil at high vacuum, in the millibars range ), so a higher vacuum corresponds to a lower pressure drop (equivalent to a larger column diameter) with an important economic advantage.

In order to reduce the bottom temperatures, falling film reboilers are generally used with very low temperatures differences with the heating medium.

This type of technology has been key in bringing multiple advantages to the edible oil refining process:

• Increased product value
• Increased versatility for different industries
• Optimization of resource
• Strong reduction in waste
• Improved environmental sustainability of the entire refining process
• High production flexibility

FURTHER ADVANTAGES OF CMB TECHNOLOGY

Both fatty acids fractional and total distillation are mature technologies, but that is precisely why excellence lies in the details.

CMB is able to dynamically satisfy even the highest quality requirements of Clients who need to obtain fatty acids with the highest possible quality level, always offering flexibility at the highest market level in terms of solutions and customer care.

Furthermore, CMB guarantees optimum values ​​ in terms of both purity and colour stability, by adopting columns operating at low temperatures and with reboilers having low temperature differences between the heating medium and the product. These systems – designed, engineered and manufactured by CMB – include heat recovery with exchangers between the feed and output products (sensible heat) and low-pressure steam generation for condensation heat (latent heat).

in this case, the CMB design also provides the possibility of recovering latent heat by generating low-pressure steam that can be used for tank tracing and heating, demonstrating – once again – that environmental sustainability and economic viability can coexist when a company adopts an approach that combines competence, professionalism and experience.

To sum up, the main advantages of the CMB’s fatty acids distillation technologies, can be resumed as follows:

• Tailor-made design right from the first offer
• Highly optimised systems
• Best-in-class materials
• Advanced and proactive customer care
• Competitive investment costs

Take the opportunity now to contact a CMB specialist for more information and find a reliable partner for your business. Write now to: info@cmb.it, we will help you to find the best solution for your Company.