Which Vacuum Pump Fits Which Chemical Process?

The efficiency champion takes the price! Dry compressing screw vacuum pumps with a particularly high degree of efficiency in the chemical production are challenging liquid ring pumps. At first sight, it seems clear which principle leads the way. However, this may be delusional.

In many cases, vacuum per se is an energy-saving measure. Many chemical reactions are accelerated by vacuum which allows the reduction of distillation temperatures required for the thermal separation of substances. Vacuum, however, costs energy and depending on the technology employed, this can come quite costly. Furthermore, it provides safety, e.g. if process vessels are evacuated, preventing dangerous reactions with oxygen, which can lead to an explosion.

However, vacuum pumps can also become a safety problem, if they are not designed properly or suitable for the application. In order to be always on the safe and efficient side, high competence is required, and this is in the most diverse fields of application.

It starts with the chemical processes: Quite a few reactions are only performed under vacuum or are at least unprofitable without vacuum. From evaporation, sublimation and rectification through filtration and drying to vacuum conveying: vacuum technology is almost ubiquitous in chemistry. The vacuum areas involve approximately by five powers of ten — from 10^-2 to 1000 hPa. There is no single-pump system which operates optimally in the entire region. Mechanical vacuum pumps are usually used, and even often combined by the displacement type (liquid ring, rotary vane and roots pumps) as well as liquid, gas or water jet pumps, hence propellant pumps.

For optimal design and configuration of a vacuum system, it is not sufficient to consider the type of the process and the physical details (e.g. incidental gas/vapor quantity and operating pressure). The medium to be conveyed and its properties are also taken into consideration. There is even a challenge for new processes: all matters are taken into consideration during planning.

When a user has no experience gained with an existing system of the same type, uncertainty is often balanced with overdimensioning. In the extreme case, it can even lead to destruction of the vacuum system, unless all contingencies were considered beforehand. Not to be underestimated is the starting-up phase, in which possibly other substances could be conveyed as in the current process — substances that can damage certain types of vacuum pump types.