Planning a fatty acid distillation plant? Here’s what every manufacturer should know

Introduction

Are you planning to set up a fatty acid distillation plant? Given the growing demand for high-purity fatty acids from industries like food, cosmetics, personal care, paints, and lubricants, that is an increasingly lucrative business opportunity.

The scientific community knows of over 1,000 distinct fatty acids, which are naturally occurring components of fats, oils, and other similar compounds. They differ in alkyl chain length, typically having ten or more carbon atoms. They contain diverse functional groups along these alkyl chains. And they have anywhere between zero and six carbon-carbon double bonds with cis-or trans-geometry.

Not all of these fatty acids have industrial applications. About 20 to 25 of these 1,000+ fatty acids are produced from commodity fats and oils and are used in the food production, oleochemicals, and biodiesel industries.

In the oleochemicals industry, a fatty acid distillation plant is really a fatty acid and glycerin plant. This is because the process used to produce fatty acids i.e. splitting or hydrolysis involves the reaction of the fat/oil with steam/water to form crude split fatty acids and glycerin dissolved in water.

Such a fatty acid distillation plant will usually include equipment for not just the fatty acid distillation process. It may also comprise setups for feedstock pretreatment, splitting or hydrolysis, straight distillation, fractional distillation, sweet water (glycerin + water) treatment and evaporation, fractional crystallization, hydrogenation, and glycerin distillation and refining.

Before you take your first step towards setting up your new fatty acid distillation plant, here are the basics you should know:

What is fatty acid distillation?

Fatty acid distillation is an essential step in the process of refining crude fatty acids obtained from the splitting or hydrolysis of oils or fats. These crude fatty acids contain impurities like oligomers, oxidation products, glycerides, and other odoriferous compounds. They also contain unconverted mono-, di-, and triglycerides.

The fatty acid distillation process involves the distillation of these crude fatty acids under vacuum and high temperatures. The process is designed to purify these fatty acids by separating them based on their different relative volatility at different pressure and temperature conditions. This is done to meet quality standards like colour and purity.

The fatty acid production process

As we've already discussed, fatty acid distillation is only one step in the fatty acid production process.

The first step is the splitting or hydrolysis of the triglycerides in naturally occurring oils and fats. The triglycerides react with water to produce crude fatty acids and glycerine.

What you should know: Splitting is carried out using either batch processing (employing an accepted industrial process like the Twitchell process) or continuous processing (like the Colgate-Emery process). The latter is usually preferred as the resulting fatty acids are significantly lighter in colour.

Beyond the type of process used, the degree of triglyceride hydrolysis also matters as a lower degree of hydrolysis will result in more residual mono-, di-, and triglycerides and free glycerin in the crude fatty acid. Consequently, this will result in more distillation pot residue after the fatty acid distillation process.

Regardless of the approaches used, the fatty acids derived from splitting or hydrolysis will have a relatively dark colour and many impurities. Your fatty acid distillation plant will purify the crude fatty acids and/or separate them into fractions through the process of fractional distillation.

The fatty acid distillation process

The fatty acid distillation process is far from new. It has been practised for over a century. Even today, it remains the most common method to produce high-purity fatty acids because it removes both low- and high-boiling impurities and odoriferous substances.

Like with splitting, fatty acid distillation may also be a batch or a continuous process.

Additionally, it may be a simple distillation process to purify the crude fatty acids or a fractional distillation process to not only purify the crude substance but also separate fatty acids based on their chain length and boiling characteristics.

What you should know:
-          Coconut oil and palm kernel oil can be used to produce pure fractions of short-chain fatty acids like C8, C10, C12 and C14. They can also be used to produce a mixture of C8 and C10, C12 and C14, and C16 and C18 fatty acids. Similarly, palm oil can make C16 and C18 pure fractions as well as a mixture of the two. Meanwhile, mustard oil can produce fractions rich in C18 and C22 i.e. behenic acid and erucic acid.

-          Fatty acids are inherently heat-sensitive. That's why your distillation method should employ as low a temperature as possible while aiming for the shortest residence time of the fatty acid in the distillation unit. Generally, fatty acid manufacturers conduct the fatty acid distillation process at temperatures between 160 and 250⁰C and pressures between two and 20 millibars.

-          Volatile compounds, called "light ends", may be released during fatty acid distillation. These compounds are cooled, condensed, and then either further processed or simply discarded appropriately.

-          Trace amounts of fatty acids remaining in the residual matter after distillation may be either repurposed for lower-grade applications or reprocessed through re-hydrolysis and subsequent batch distillation. The latter approach helps maximise fatty acid recovery.

Boxes to check before getting in touch with a fatty acid distillation plant manufacturer

Now that you have the basics of fatty acid distillation down, you're probably rushing to get in touch with a fatty acid distillation plant manufacturer so that you can get your project off the ground.

Before that, however, you have some homework to do:

Understand your feedstock and your product requirements. Your choice of feedstock will likely depend on what is available in your region of operations. Your choice of feedstock will determine the chemical characteristics you are working with - think chain length, saturation, boiling point, etc. Whether you're using palm oil, coconut oil, tallow, or any other fat/oil, understand the feedstock well so that you can choose the right approach to distilled fatty acid production.

You must also have clarity on the kind of final product you want to make and the industry it is appropriate for. Do you need highly pure fractions? Do you need to separate short- and long-chain fatty acids? Will your distilled fatty acids be ultimately used in the cosmetics, food, or tyre industry?

Choose the right distillation technology. Depending on your desired purity and throughput, you may choose vacuum distillation, molecular distillation, falling film or wiped film evaporators, or fractional distillation columns. You also need to make decisions about operating pressure, reboiler and condenser design, and internal column configuration i.e. trays vs structured packing. You must discuss your product requirements with your potential fatty acid distillation plant manufacturer to ensure that they can incorporate your requirements in your plant design.

Choose the right materials. Since fatty acids can be corrosive, especially under the conditions required for distillation, select corrosion-resistant alloys like stainless steel 316L or higher. Your project's specific fatty acid profile will require specific materials and conditions, so ensure that your fatty acid distillation plant manufacturer conducts a thorough corrosion analysis.

Compliance is key. Given the potential risks to personnel safety and product quality during fatty acid distillation, your fatty acid distillation plant must comply with industry standards such as those set by the ASME for pressure vessels, the NFPA for fire safety, or any other regulations concerning health, safety, and the environment.

At the end of the day, setting up a fatty acid distillation plant is a significant undertaking. Nonetheless, with the right planning and technical expertise, you can set up a highly profitable operation. It all depends on your engineering partner.

Partnering with an experienced EPCC company can not only save you time but also reduce your risks and ensure long-term success for your fatty acid distillation plant. That's exactly how our expert team at Kumar can help you - we can help you build an efficient and profitable fatty acid distillation plant which can evolve with market needs.

Reach out to our expert team today.