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Vacuum Distillation

Distillation with vacuum. A technique used to gently separate compounds from a liquid. By lowering their boiling point with the help of vacuum.

distillation

How does vacuum distillation work?

Vacuum distillation is an important process in the chemical and pharmaceutical industry. But it is employed in many other sectors, too. For example, in beverage and food production to extract plant essences, or to separate long-chain hydrocarbons in oil refineries.

Distillation is commonly used to separate the components of a liquid mixture. As the liquid components have different boiling points, they evaporate under different operating conditions. And may be removed and recovered successively.
The boiling point of the substances to be separated is lower under vacuum.

Vacuum distillation is therefore the process of choice if the compounds to be separated normally have a high boiling point or are explosive. And allows for separation of substances that would decompose at higher temperatures.

Busch vacuum technology in distillation

For use in distillation processes, we offer a wide range of vapor-tolerant, corrosion-free vacuum solutions. As well as ATEX versions to deal with flammable vapors, gases and liquids. Thanks to our global network, we can also comply with other local explosion protection regulations. Such as Ex-Proof, KOSHA, etc.

Learn more about vacuum distillation

How does vacuum distillation work?

Distillation is the process of separating the components or substances from a liquid mixture.
The process is based on differences in the relative volatility of the different components.
In vacuum distillation, vacuum is used to lower the boiling point of the substances to be separated.

Where can vacuum be used in distillation processes?

Some compounds have very high boiling points. In this case, vacuum can be used to lower the boiling point instead of increasing the temperature. Once the pressure is lowered to the vapor pressure of the compound, the distillation process can start. This technique is referred to as vacuum distillation.

What are the advantages of vacuum distillation over atmospheric distillation?

The boiling point of the substance to be separated is lower under vacuum.
Vacuum distillation is therefore the process of choice if the compounds to be separated normally have a high boiling point or are explosive.

Using vacuum in distillation processes thus offers several advantages:

  • energy savings achieved by reducing the required heat
  • increased yield thanks to reduced side reactions
  • higher uptime thanks to reduced contamination of the devices
  • increased safety thanks to a lower risk of explosions
  • possibility to separate substances that would decompose at higher temperatures

What are the best vacuum pumps for distillation?

The most frequently used vacuum pumps for distillation are dry screw vacuum pumps. Thanks to their dry operating principle, the process gases are not contaminated.

Liquid ring vacuum pumps can also be suitable. Using the distilled product as an operating fluid allows condensation inside the liquid ring such as in monoethylene glycol (MEG) regeneration.

Once-through oil-lubricated rotary vane vacuum pumps are the products of choice whenever a process is corrosive or can polymerize. Oil-lubricated rotary vane vacuum pumps are an excellent solution for light applications.

Vacuum boosters can also be used to increase the pumping speed and/or reach a lower operating pressure.

How do vacuum distillation systems work?

Vacuum distillation systems are often a combination of a volumetric vacuum pump (like COBRA, DOLPHIN, HUCKEPACK or R5) and a condenser used to collect the valuable compounds. The condenser can be installed upstream or downstream of the vacuum pump, according to the process requirements.

A vacuum distillation system usually consists of the following core components:

  • Reaction vessel or heater
    Heats up the mixture and boils off the “light” compound with the lowest boiling point.
  • Fractionating column
    Enhances the separation to get a purer product.
  • Condenser
    Brings the vaporized compound back to the liquid state.
  • Receiving vessel
    Collects the purified compound.
  • Vacuum pump
    Reduces the pressure in the system.

The vacuum system removes the non-condensables and the fraction. The result is a lower pressure in the system. This, in turn, leads to a lower boiling temperature (called sensible heat) which goes hand in hand with energy savings and a higher yield.

What are the key points to consider when buying a vacuum distillation system?

There is no one-size-fits-all solution when buying a vacuum distillation system. Different parameters have to be taken into account to provide the most efficient solution.

Peace-of-mind solution

The best vacuum system is the one you never have to worry about. It should deliver the required performance. And run seamlessly and reliably. This is achieved by a combination of the right technology integrated in a suitable skid. Combined with the required protection and safety sensors. The right operating procedures including warm-up and shut-down cycles are also key factors for trouble-free operation. A vacuum distillation system can also include redundancy. To increase the reliability of the system and to reduce the downtime by allowing maintenance without process downtime.

Safety

A vacuum distillation system should never pose a danger to your co-workers. This is especially important whenever explosive, flammable and toxic compounds are handled. In this case, the vacuum system needs to comply with the local explosion regulations such as ATEX, IECEX, Ex-Proof or KOSHA. The right level of leak-tightness is also crucial to prevent any leakage of toxic compounds. In this case, specific options such as double mechanical seals and barrier gases are recommended.

Cost of ownership

Focusing only on the initial investment costs is usually not the best way to optimize the total cost of ownership of a vacuum distillation system. Several other parameters have to be taken into account. To choose the right technology on the one hand and to adapt the system design on the other hand. The main points to consider are the consumption of cooling water, operating fluid, flushing liquid or other. But also, the costs for waste treatment such as the treatment of water contaminated by the operating fluid. The frequency and cost of maintenance should also be taken into account. Finally, it is important to take a holistic look at the vacuum system. Pipes that are too small, for instance, can greatly impair the performance of the system.

Energy efficiency

The energy consumption of a vacuum distillation system is a key selection factor. Depending on the operating pressure, different technologies can be considered. For low pressures and high volume flows, a multi-stage design including vacuum boosters can be a cost- and energy-efficient solution. Additionally, the regulation of the vacuum demand is key. Nowadays, most systems can be operated with a variable speed drive to reduce power consumption when vacuum demand is low.

Extended lifetime

To extend the lifetime of a vacuum system, several parameters should be considered. One of them is the use of the right technology and the right pump configuration. This includes the appropriate sealing liquid, construction and sealing materials for the chemicals reaching the vacuum system. Another one is the proper use of the system. In most cases, warm-up and shutdown cycles, including clean-in-place (CIP), are required to maintain performance at factory standards.

Money savings by system upgrade

Your process, including vacuum demand, may have changed. This leads to the question, whether your system is still adapted to your needs. And whether it is still operating as energy-efficiently as possible. When it is time to upgrade or replace a vacuum system, it is worth looking at the entire installation. To identify any potential for optimization. Modern technologies can make it possible to save money by reducing operating fluids and energy consumption. For example, by switching from steam jets to dry solutions.

Process gas

Depending on the composition of the process gas, it may be valuable to recover or neutralize it. A dry solution, for instance, allows the recovery of non-contaminated process gas at the exhaust of the vacuum pump. Operated with the right operating fluid, a liquid ring vacuum pump can be an efficient neutralization system. APOVAC, for example, has been specially designed for this purpose.

Which vacuum pumps from Busch are especially suitable for distillation processes?

The choice of the vacuum pump depends on the respective process reqiurements. Most suitable products are COBRA, DOLPHIN, HUCKEPACK or R5 vacuum pumps and vacuum boosters.

What are some examples for the use of Busch vacuum technology in distillation applications?

Busch solutions are used in most vacuum distillation processes.
From the crude oil distillation in refineries to the preparation of API (Active Pharmaceutical Ingredients) in the pharmaceutical industry. They are also widely used in the agrochemical industry as well as in flavors and aromas extraction and preparation.

How does the distillation of crude oil work?

Crude oil must be broken down into its components in order to produce petrol, diesel, aviation fuel or heating oil. This process takes place in oil refineries by means of distillation.

As crude oil contains heavier and lighter hydrocarbons with different boiling points, two distillation processes are necessary. After atmospheric distillation, a second distillation is carried out under vacuum. In this case, vacuum distillation allows to separate heavy hydrocarbons at only slightly higher temperatures. Which, in turn, minimizes cracking of components and the creation of unwanted by-products.

Vacuum distillation in the chemical and pharmaceutical industry

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Getting pure compounds is the goal of many processes in the chemical and pharmaceutical industry. One of the most commonly used techniques to extract compounds of interest from the reaction mixture is distillation.

Carrying out distillation under vacuum allows for a gentler treatment of heat-sensitive compounds. Thanks to lower process temperatures, the yield of the distillation process can be improved by preventing polymerization, cracking or other product degradation. And significant energy savings can be achieved.

Vacuum distillation is therefore the perfect choice for a wide range of separation processes in the chemical and pharmaceutical industry. From Active Pharmaceutical Ingredient (API) manufacturing or monomer purification to natural compound extraction. As well as for chemical synthesis, the preparation of flavors and aromas and many more.

Matching products

Vacuum distillation in the oil and gas industry

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Crude oil distillation

In order to produce petrol, diesel, aviation fuel or heating oil, crude oil must be broken down into its components. This process takes place in oil refineries by means of distillation. As crude oil contains heavier and lighter hydrocarbons with different boiling points, two distillation processes are necessary.

After atmospheric distillation, a second distillation is carried out under vacuum. To separate heavy hydrocarbons at only slightly higher temperatures. This minimizes cracking of components and the creation of unwanted by-products.

Matching products

One of our implemented vacuum distillation systems

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Challenging requirements
  • Large volume flow
  • Working pressure of 8 mbar

Our solution
  • 2 stages of vacuum boosters with intercondenser

Products inside the vacuum system

Vacuum distillation of essential oils

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Our experience

Capua 1880 uses vacuum technology from Busch Vacuum Solutions for the distillation processes, which are carried out in thin-film evaporators or short-path distillers depending on the type of fruit. All the distillers use only COBRA screw vacuum pumps that are free of operating fluids.

The frequency-controlled vacuum pumps precisely and reliably guarantee the required vacuum level which, together with the temperature, ensures the desired product quality.

Implemented products

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