Pressure cascade

A paper mill in Central Bohemia discovered the annual cost of incorrect compressor cascade pressure settings. Its station consists of two load/unload compressors. The first is set to 6.4/8.0 bar, the second to 6.3/8.1 bar.

It is immediately apparent that both compressors will react to a system pressure drop at the same time.

The reason is the minimal 0.1 bar difference between their loading pressures; this should be at least 0.5 bar. We proposed replacing the current setup with a 15 kW variable-speed compressor and calculated savings of CZK 220,000 from total electricity costs of CZK 300,000.