Many engineers know that oil purifiers can remove moisture and gas, but they are unclear why a two-stage system is more effective than a single-stage one and why temperature and vacuum levels need to be used in conjunction. By explaining this principle clearly, operators will understand which parameters cannot be arbitrarily adjusted and why.

The principle of the saturation vapor pressure of water

Under normal atmospheric pressure (101,325 Pa), water boils at 100°C. However, the boiling point decreases as the air pressure drops—under vacuum conditions, water boils (vaporizes) at much lower temperatures. This is the core physical principle of vacuum dehydration.

When the oil is heated to 40～70°C and simultaneously maintained in a high vacuum environment of ≤5Pa:

Water that requires 100°C to boil under normal pressure can vaporize at just about 4°C under vacuum

The moisture dissolved in the oil (including free water and dissolved water) rapidly transforms into vapor and escapes

Dissolved gases (O₂, CO₂, hydrocarbon gases, etc.) also desorb from the oil under low pressure

Atomization increases the contact area

After the oil enters the vacuum tank, it passes through the unique atomization device of the HZLY-200A, transforming into fine mist droplets. The purpose of atomization is to expand the oil's surface area by tens or even hundreds of times, significantly accelerating the evaporation rate of moisture and gases—this is why atomization treatment is much more efficient than overall liquid surface evaporation under the same vacuum level.

T-type vacuum degassing tank

The HZLY-200A adopts a T-shaped tank design: the horizontal tank is used for degassing (where oil is atomized and water vapor is extracted), while the vertical tank serves as temporary storage for the degassed oil, awaiting discharge by the oil pump. This design separates degassing and temporary storage, preventing the degassed oil from being re-exposed to air-containing incoming oil, resulting in a degassing efficiency over twice that of conventional "three-dimensional flash evaporation" designs.

The Quantitative Advantage of Dual-Stage Vacuum

Roots pump (ZJP-300, 1080m³/h) and rotary vane pump (200m³/h) in series: The rotary vane pump establishes the initial vacuum, while the Roots pump significantly enhances the pumping speed on this basis. The two-stage combination achieves an ultimate vacuum of ≤5Pa, which is over 10 times lower than the 50～100Pa of a single-stage rotary vane pump. The corresponding differences in water's boiling point and gas desorption rate are even exponential.