Air Separation

Cryogenic production

Cryogenic production is the separation of air by fractional distillation at very low temperatures where the components of the air are liquid. The air is cooled down to -185° C by refrigeration processes. In the following distilling process the required products are produced. The gaseous products and waste streams are then warmed. The products are now available for packing in high pressure cylinders or pipeline delivery. This process reaches the highest purities of the required products (e.g. ~99.5% with O2). The low temperatures of the handled gases require a compressor solution that is insensitive to these low levels of temperature. To obtain a high level of gas purity and to mitigate the risk of explosions (e.g. with O2) of oil vapours an oil-free and contactless (no abrasive wear) compressor solution is mandatory.

The contactless and oil-free Laby® Compressor solution is the solution of choice since the labyrinth sealing on pistons and piston rods is insensitive to temperature changes. No hotspots due to sealing ring friction occur and no contamination of the valuable gases with oil or abrasives can happen.

 

Non-cryogenic production

Non-cryogenic production as the separation of air at near ambivalent temperatures requires the Pressure Swing Adsorption (PSA) process. A special adsorptive material (e.g. zeolites) in a pressurised (1 – 3 bar) vessel adsorbs the relevant gases (N2, CO2, etc.) from the air according to the molecular properties. A purity of 90 – 95 % of Oxygen can be achieved with this process. By lowering the pressure (“Swinging” from high to low pressure) the “waste gas” can be desorbed and purged out of the vessel. Operating two or more vessels in parallel allows near continuous production. Alternatively the Vacuum Pressure Swing Adsorption (VPSA) can be used. The only difference to the PSA is, that vacuum blowers are used to reduce the desorption pressure in this kind of process. The lower desorption pressure allows much lower inlet pressures. In general these systems are more costly but more energy efficient for the same product flow and purity conditions.

The oil-free and contactless Laby® Compressor solutions is the solution of choice for the air compression and produced gas (e.g. O2, N2).  Burckhardt Compression offers its compressor solutions as complete turn-key installations, engineered packages or bare shaft compressors. Our in-house competence includes compressor design and sizing, pulsation and vibration studies, plant engineering, instrumentation and PLC programming.