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Vacuum Degassing

Vacuum degassing. A technique for removing dissolved gas from a liquid or paste. By lowering the pressure in a container with the mass.


How does vacuum degassing work?

Degassing of liquid, paste-like and moist products is one of the most important applications of modern vacuum technology.

Gases, vapors and moisture are extracted from the processed material. Under vacuum. The result: higher product quality.

An example: the degassing of plastics during extrusion.
Trapped moisture and gases are extracted directly at the extruder screw zone. Significantly improving the structure and physical properties of the final product.

Busch vacuum technology for degassing

We offer a range of standardized vacuum systems specially designed for extrusion processes. They include separator/filter units to condense the extracted vapors and gases.

Our project engineers will recommend the optimum system. Precisely matched to your extruder throughput and raw material.

Learn more about vacuum degassing

What is vacuum degassing?

Every substance changes according to temperature and pressure. Mixtures of substances can therefore be separated when one substance evaporates at another point than the other. Under vacuum, evaporation is possible at lower temperatures. This technique can be used in degassing processes. To remove dissolved gases from liquids, especially water or aqueous solutions.

According to Henry's law, the amount of dissolved gas in a liquid is proportional to its partial pressure. So, placing a solution under reduced pressure makes the dissolved gas less soluble. Sonication and stirring under reduced pressure can usually enhance process efficiency. This technique is often referred to as vacuum degasification or simply degassing.

How does a vacuum degassing system work?

Vacuum degassing systems are often a combination of a vacuum pump and a trap. The vacuum pump reduces the pressure inside the system. The trap protects the vacuum pump by preventing liquids and particles from reaching it. In the cases of heavy condensable loads, a condenser can be used to collect the valuable compounds. It can be installed upstream or downstream of the vacuum pump, according to the respective process requirements.

Where is vacuum used in the degassing process?

Vacuum is used in degassing installations like extruders, columns, or mixers. Vacuum degassing plays an important role in different applications such as:

  • Sea water deaeration on offshore platforms
  • Degassing of creams and pastes before bottling
  • Degassing of solvents in the chemical industry to avoid side reactions
  • Steel and metal degassing to produce purer grade
  • Degassing of plastics to reduce the odor and improve the transparency and reliability of the product

Degassing under vacuum is only possible if the substances to be separated have different evaporation points.

What are the advantages of vacuum degassing over alternative degassing technologies?

Under vacuum, the evaporation of the gas can take place at a low temperature. This offers several advantages:

  • Energy savings compared to thermal degassing
  • Time and energy savings compared to pump-freeze-thaw cycles
  • Lower investment costs compared to membrane degassing
  • Less consumption of inert gas compared to sparging
  • Protection of the remaining substances against thermal degradation
  • Separation of components at defined physical conditions
  • Controlled handling of the gas portions
  • Control and possible reproduction of the operating conditions

What are the best vacuum pumps for degassing?

An important prerequisite when choosing the right vacuum pump for degassing is that it reaches the expected pressure range for the process step. Moreover, the vacuum pump should be able to handle liquids and small particles.

Typical vacuum pumps for vacuum degassing are liquid ring vacuum pumps, claw vacuum pumps and dry screw vacuum pumps.

Liquid ring vacuum pumps are the perfect choice for vacuum degassing as the vacuum pump often comes in contact with condensable vapors. The condensation of such vapors in the liquid ring is very efficient. Dry screw vacuum pumps are perfectly suited whenever the vapors can be valorized if not contaminated. Oil-lubricated rotary vane vacuum pumps are excellent when accumulation can be avoided in the oil.

What are the best vacuum pumps from Busch for the degassing process?

The choice of the vacuum pump depends on the respective process requirements. The most suitable and proven Busch products for degassing are MINK, COBRA, DOLPHIN, HUCKEPACK and R5.

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

Busch solutions are used in all kinds of degassing applications. DOPHIN vacuum pumps, for example, play an important role in processes like sea water deaeration on offshore platforms or sparkling water degassing. Dry screw vacuum pumps are used in pharma and in the cosmetic industry to degas creams and pastes. Our vacuum technology is also present in plastics degassing in compounding processes, and in water degassing for recycling processes and food applications. Another possible field of application is the degassing of solvents in the chemical industry to avoid adverse side reactions. But also degassing of steel and metal to produce a purer grade.

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

You should consider the following in order to find the vacuum degassing solution that best fits your needs:

  • Number of dissolved gases to be removed
  • Mass or volume flow of gases removed
  • Required system pressure
  • System operating temperature
  • System volume
  • Processing time required to achieve the system pressure
  • Leakage rate of air into the system
  • Available steam pressure, temperature, and flow
  • Available cooling water temperature and flow
  • Cost of steam and electricity

Melt degassing

Bada AG produces high-quality, technical thermoplastics and thermoplastic elastomers for various industries. In 2001, Bada was one of the first companies ever to use MINK claw technology for degassing the melt during extrusion.

Replacing the previously used liquid ring vacuum pumps by dry claw vacuum pumps from the MINK family led to the possibility of extracting gases and vapors from the melt without any operating fluid.

With MINK vacuum pumps, no water needs to be supplied and discharged anymore and there is no more need for a cooled water circuit. All associated costs such as installation, consumption, control, and maintenance of the water supply could thus be eliminated.

Vacuum degassing in the plastics industry

Extrusion is a common process in the plastics industry to melt, mix and homogenize plastics. The raw material is conveyed by a screw in a heated barrel. There, the plastic is melted by friction and heat to a viscous liquid. Which is then forced through a die into its final shape.

During the melting process in the extruder, the residual moisture evaporates. And, due to the increase in temperature and pressure, gases can sublimate from the plastic.

Vacuum ensures that these trapped vapors and gases are reliably extracted from the melt. For a high-quality final product without voids or other imperfections.

Vacuum degassing in the beverage industry

Rheinfelsquellen H. Hövelmann GmbH & Co. KG is one of Germany's largest private wells.
Liquid ring vacuum pumps were used at all filling plants for degassing the well water. The energy and water consumption were huge.

A MINK claw vacuum pump was installed at one plant on a trial basis. It was a success. Rheinfelsquellen achieved its aim of making a huge cut in water consumption. And finally converted three more filling plants to this modern vacuum technology.

How does vacuum degassing in the beverage industry work?

For many beverages, a precise quantity of dissolved carbon dioxide is essential. This applies not only to the production of mineral water, but also of soft drinks or even beer. However, the amount of CO2 in spring water may vary.

To overcome this problem, several processes are required. And in every step, vacuum plays an important role.

The CO2 is first extracted from the spring water by a vacuum deaeration system. It is then cooled and liquefied. Finally, it is reintroduced in precisely dosed quantities to the final product at the bottling stage. For consistent quality and a refreshing experience.

Vacuum degassing in other industries

Vacuum degassing in the steel industry

Vacuum degassing has become a crucial process in modern steel production. For example, it is the only way to manufacture certain grades of highly stressable steel alloys. Used in the automotive, aerospace and railway sector.

During the production process, molten steel can become infused with excess amounts of hydrogen and carbon. These imperfections affect the integrity and performance of the steel making it less ductile and thus less malleable.

In the past, hydrogen removal required the metal to be cooled down slowly. Thus, extending the manufacturing process. The modern method is to extract hydrogen under vacuum. For faster productionof high-quality steel with precisely defined properties.

Our solutions

Vacuum degassing in the oil and gas industry

Vacuum deaeration is a commonly employed method in the oil and gas industry today. Packed towers are continuously evacuated with vacuum systems. Thus, extracting oxygen and other gases.

In offshore applications, the injection of seawater into the oil well is an essential procedure in crude oil production. It is often a crucial factor in achieving and sustaining economically viable production rates.

The water used has to be deaerated before. Because the oxygen would have an adverse effect on sulphate removal systems. Everything for a stable and economic production.

Our solutions

Vacuum degassing in practice

  • Modern Vacuum Technology for Melt Degassing During Extrusion

    Modern Vacuum Technology for Melt Degassing During Extrusion

    PolyComp GmbH

    Learn more
  • Complete Vacuum Supply with MINK Claw Vacuum Technology

    Complete Vacuum Supply with MINK Claw Vacuum Technology


    Learn more
When it comes to reliability, maintenance effort and economic efficiency, we made the right choice opting for the PLASTEX degassing system.