Comparison of low-pressure oil-free screw and low-pressure oil-injected screw machines

As the country pays more and more attention to energy conservation and emission reduction (fashionable name is carbon neutral), the application of low-pressure screw air compressor is also increasing.

At present, low-pressure screw machines are mainly divided into three types: dry screw, water injection screw and oil injection screw. Among them, dry screw and water injection screw have a wider application range due to their characteristics of exhaust oil-free (oil-free screw machines can be basically used in all fields where oil injection screw machines can be applied). Common oil-free low-pressure screw machines are applied in biological fermentation, pneumatic conveying, glass bottle blowing, LP spray gun, etc. HVoil injection screw machines, etc, it is also used in some pneumatic conveying fields where the conveying material is not afraid of oil, and fermentation is generally rarely used.

Regarding energy consumption, many people may think that the oil-injected low-pressure screw machine is more energy-efficient when looking at the sample data, but in fact it is just the opposite. Take 17m & sup3, which is commonly used for pneumatic conveying./min air-cooled air compressor as an example, the power of low-pressure oil-free dry screw shaft is about 54KW, and the specific power is about 3.2Kw/(m & sup3;/min), while the nominal power of low pressure oil injection screw machine is 55KW, however, the specific power can reach 4.5Kw/(m & sup3;/min), which is already very good. The brand that can really achieve this specific power is definitely a conscience brand.

The energy consumption of water spray low-pressure screw is basically close to that of oil spray screw machine, while the stability of water spray screw machine has been poor, including foreign brands, so it has always been non-mainstream. The main reason why the energy consumption of the oil injection screw machine is not good is that in order to maintain a good oil and gas separation effect, the system must maintain a minimum pressure (all oil injection screw machines have a minimum pressure valve, the reason is that), generally more than 3bar, even 4.5bar, which will inevitably lead to over compression. The oil-free dry screw does not need a minimum pressure valve and there is no over compression, and the energy consumption of the compressor is proportional to the pressure, therefore, the energy consumption of low-pressure oil-free dry screw is far better than that of low-pressure oil-injected screw machine.