Efficient Material Separation: Use of bellows pulsators in extraction processes

In the chemical and pharmaceutical industries, mixtures of substances must often be separated. However, if the substances to be separated have similar boiling points or the energy required must be minimised, conventional extraction processes quickly reach their limits.

Instead, extraction processes in which the substance mixtures are pulsed in extraction columns make technical and economic sense. The bellows pulsator from LEWA ensures particularly harmonious pulsation that is gentle on both the medium and the system itself.

Thanks to precisely adjustable amplitude and frequency, the system can be optimally adapted to different mixtures of substances and separation tasks. Because the robust, low-maintenance bellows pulsator also relies on the proven modular system from LEWA, a high degree of variability in stroke volumes is possible. 

Industrial extraction plants often work with complex fluid mixtures that must be processed in large quantities under constant conditions. In continuous-flow extraction columns, insufficient mixing can lead to the inefficient separation of substances, which in turn has a negative effect on the purity of the end product and slows down the entire process. In such cases, large quantities of the fluids remain unused, which leads to product loss and higher operating costs.  

This can be remedied by pulsating extraction processes in which pulsating movement yields high separation with low energy consumption. The required intensive mixing of the phases at the column bottoms is achieved by bellows pulsators. The pulsators are suitable for use in both sieve tray and packed column extractors. 

Extraction columns with a height of up to 18 m can be fed  

Extraction columns with a height of up to 18 m can be fed with LEWA pulsators. To date, stroke volumes between 0.2 and 28 l at stroke frequencies between 20 and 160 strokes per minute have been realised. LEWA achieves high stroke volumes in the latest systems by electronically synchronising individual pulsators. The bellows are powered with exceptional efficiency thanks to mechanical drive units from the LEWA modular system. "They work according to the variable eccentric principle, which means that the stroke length can be infinitely adjusted very precisely during operation. In combination or separately, the stroke frequency can also be varied using a frequency inverter," explained Karl-Heinz Vogler, head of sales division process industry & downstream at LEWA.  

Thanks to its robust design, the bellows pulsator can operate continuously. The wetted components are made of hygienic stainless steel and PTFE. In addition, a gas cushion-supported pressure equalisation system extends the service life of the bellows and minimises the drive energy required to trigger the pulsations. "This significantly reduces operating costs, especially with high pulsation volumes and column heights," added Vogler.  

Comprehensive leakage monitoring for operation in Ex-areas 

The leakage monitoring integrated into the bellows ensures safety during operation. A sensor detects fluid leaks at an early stage and triggers an alarm or automatically stops operation. The nitrogen pressure behind the bellows is also continuously measured and can be adjusted to the respective process. This stabilises the movement of the bellows, which reduces wear and supports harmonious pulsation. The nitrogen atmosphere on the back of the bellows also ensures safe operation in Ex-zones, and ignitable mixtures inside the pulsator are avoided in case of failure. 

High flexibility is not only evident in the stroke and volumes, but also in the degree of possible adjustments to the system: the connection geometry of the bellows pulsator is matched to the extraction column. "When we plan pulsators, we take material requirements and special design features into account to ensure that the pulsators are designed precisely for the subsequent operating environment before delivery. This includes, for example, installing multiple pulsators on rails, which enables the bellows to be replaced quickly and easily," said Vogler in summary.