In the 19th century, only two types of compression principles were popular, positive displacement, known as piston type, and the centrifugal type.
Both were the standard up to the 60ies, but were not reliable enough to keep factories running. The piston compressors were large and required frequently maintenance. The materials and development techniques available in those days, were not sufficient to make the machines solid and reliable. The efficiency of the piston compressor was already at a higher level than today's state of the art Oil-free compressors. However the reliability was not up to the required level. The same was happening in the car industry with the engines.
In the seventies, the Screw air-compressor was developed. Two variants were introduced, the Oil-flooded and the Oil-free screw compressors. The important benefit was the continuous duty. The rotary machines, could run a whole year with planned interventions and the factories could operate without interuptions ! Only disadvantage is that the energy consumption of the rotaries is importantly higher than the piston compressor.
The car industry also experimented with the rotary motors such as the rotary Wankel motor or gas turbines. But during the oil-crisis in the seventies, the car manufacturers, concluded that only the piston engine could achieve the superior performance, lowest fuel consumption and obtain the required reliability.
In the Industry, the energy conscious thinking was not present. The cost of production stops is far higher than the cost of lower energy efficiency.
The rotaries replaced gradually alot of the piston compressors in the range up to 7-13 bar and below 350 kW. On top, the aftermarket for the rotaries is much more attractive for the compressor manufacturers than for the piston compressors, that the market got overwhelmed with the marketing of the Screw compressor as being the best modern technology.
As the Climate change becomes hot topic, the energy consumption of the compressed air installations gets more attention.
Do you believe the twin-screw is the best solution for Oil-free compressed air ?