NL Compressing Air is like squeezing an orange
The juice is coming out in high quantities, depending on the content of juice within the orange. The same is with Ambient Air, the relative humidity is defining how much water content is in the Air.
When compressing the Air, the air gets saturated and water is being condensed. As a result, latent heat is being released. Compressed Air users, don't like the presence of humidity because it can cause corrosion, freezing, and bacterial growth or disturbances in the production process. Therefor the presence of auxilliaries like water separators, Air-Dryers and filters are being present. Different types of Dryers exist, to take out the humidity to obtain the required Pressure Dew Point (PDP). Depending on the geographical region, the usage in the production process, different levels of PDP can be required. In warm countries, where freezing of water does not occur, a PDP of 2-4 deg C is often sufficient. This can be achieved with a refrigerant dryer. The cost and efficiency of these dryers is better than the once needed for PDP at -20/-40/-70 deg C. To achieve these low PDP, the most common Air-dryers are Adsorption dryers. Different types of Dessicant dryers exists, consuming different levels of energy needed to regenerate the dessicant. The energy consumption can differ a lot between different types :
Heatless dryers, often used to obtain -70 deg C, consumes the most, roughly 20% of all the compressed air produced
Heatregenerated dryers consumes, depending on the design, roughly 5-8% of the energy of the compressor power
Heat of compression theoretically consume zero energy. However, in reality, the energy consumption is related to the pressure drop which is higher and the additional electricity put into to regenerate. Often, the required dewpoint cannot be achieved without addional heating.
The auxilliaries can substantially increase the total energy consumption of your compressed air installation. Therefor, in the evaluation of the Energy consumption, the consumption of the Auxilliaries needs to be taken into account. Selection of the right Pressure Dew Point is needed, to reduce the Energy consumption of the Drying process ! Over specifying the PDP increases the energy consumption.