Air-liquid separating method and apparatus for compressed air

An air-liquid separating apparatus for compressed air, comprising:

• at least one cooling tank containing a coolant therein, the cooling tank having an inlet and an outlet, the inlet being connected with a transfer tube for transferring high pressure air, a cooling tube being disposed in the cooling tank, the cooling tube having a diameter larger than the diameter of the transfer tube, two ends of the cooling tube being respectively connected with the inlet and outlet, whereby when the high pressure air passes through the cooling tube, the high pressure air is cooled and the pressure of the vapor contained in the air is approximately the saturated vapor pressure;
• and
• an air-liquid separating tank having an intake, an exhaust port positioned in a position higher than the intake and a draining valve disposed on the bottom of the air-liquid separating tank for draining liquid water, another transfer tube being connected between the intake and the outlet of the cooling tank, whereby after the high pressure air passes through the cooling tank and flows through the transfer tube and the intake into the air-liquid separating tank, due to relief of the pressure, the temperature of the high pressure air will be approximately lowered to dew point of water, whereby the vapor contained in the high pressure air is condensed into liquid water which accumulates on the bottom of the air-liquid separating tank, while the remaining air free from water is output from the exhaust port.