Compressed air dryer

A method of drying a compressed air stream, which method comprises:

• a. passing a wet compressed air stream having a pressure of greater than about 20 psig through a first venturi tube to mix the compressed air with a liquid absorbent for the moisture in the stream;
• b. coalescing entrained liquid absorbent in the compressed air stream from the first venturi tube in a first coalescer to provide a first coalesced liquid absorbent;
• c. passing the compressed air stream from the first coalescer through a second venturi tube to mix the compressed air stream with a liquid absorbent;
• d. coalescing entrained liquid absorbent in the compressed air stream from the second venturi in a second coalescer to provide a second coalesced liquid absorbent;
• e. directing the second coalesced liquid absorbent into the first venturi to mix with the compressed air passing through the first venturi tube;
• f. removing a dry compressed air stream from the second coalescer having a dew point of 40.degree. F or lower;
• g. reducing the pressure of the first liquid absorbent to about atmospheric pressure;
• h. contacting the liquid absorbent at atmospheric pressure with a portion of the removed dry compressed air stream reduced to about atmospheric pressure to remove the moisture from the liquid absorbent to provide a dry liquid absorbent and a wet atmospheric-pressure air stream;
• i. discharging the wet air stream to the atmosphere;
• and
• j. recycling the dry liquid absorbent with an air-driven pump to contact and mix with the dry compressed air in the second venturi tube, the pump driven by a portion of the removed dry compressed air stream.

A compressed gas dryer which comprises:

• a. venturi-mixing means to contact intimately by dispersion a large volume of a high-pressure, wet, compressed gas stream having a high relative humidity with a small volume of a hygroscopic liquid absorbent miscible with the water to be removed, to disperse the liquid absorbent in microdroplet form in the gas stream, and means to separate the liquid absorbent and compressed gas by coalescence, to provide a wet liquid-absorbent mixture containing the water removed from the gas and a dry compressed gas stream;
• b. means to reduce the liquid-absorbent mixture to a lower pressure than the high pressure of the wet compressed gas stream;
• c. means to contact intimately the liquid-absorbent mixture with a portion of the dry compressed gas stream at the lower pressure, and means to separate the liquid absorbent from the gas stream, to provide a dry liquid absorbent and a lower-pressure gas stream containing the water removed from the liquid-absorbent mixture;
• d. means to recycle the dry liquid absorbent for use in the contacting of the wet compressed gas stream;
• e. means to remove the wet lower-pressure gas stream at the lower pressure;
• and
• f. means to recover a dry compressed gas stream.

A compressed air dryer which comprises:

• a. a first absorption means which comprises:
• i. a first venturi mixing tube;
• and
• ii. first coalescing means whereby a wet compressed air stream is passed through the venturi tube and mixed with a liquid absorbent and entrained liquid absorbent from the air stream from the first venturi is coalesced in the first coalescing means;
• b. a second absorption means which comprises:
• i. a second venturi mixing tube;
• ii. a source of liquid absorbent;
• and
• iii. a second coalescing means whereby the compressed air from the first coalescer is passed through the second venturi and mixed with liquid absorbent from the source of liquid absorbent and entrained liquid absorbent is coalesced in the second coalescing means.
• c. means to introduce liquid absorbent from the second coalescing means to the fist venturi mixing tube, whereby the liquid absorbent is mixed with the wet compressed air stream.
• d. means to recover a dry compressed gas from the second coalescing means;
• e. a desorption means to contact and mix wet liquid absorbent with a dry compressed air stream at a lower pressure;
• f. means to recycle wet liquid absorbent from the first coalescing means to the absorption means;
• g. means to reduce the pressure of the wet liquid absorbent recycled to the desorption means;
• h. means to introduce a portion of the dry compressed air from the means to recover into the desorption means at a lower pressure;
• i. means to discharge a wet air stream from the desorption means;
• and
• j. means to recycle dry liquid absorbent from the desorption means to the source of liquid absorbent in the second absorbent means.