High efficiency air drying system

An improved drying system for removing moisture from air used in pneumatic systems to produce product air having a dew point of about -40 to about -100 degrees Fahrenheit, which comprises:

• an air-to-air heat exchanger means to provide a precooling of inlet air to said drying system, said air-to-air heat exchanger means having a first inlet to receive said input air, a second input, a first output for withdrawing precooled air and a second outlet for delivery of said product air to said pneumatic system;
• an air-to-refrigerant heat exchanger means, said air-to-air refrigerant heat exchanger means having a first inlet connected to said first outlet of said air-to-air heat exchanger means to receive said precooled air, a second inlet to receive a refrigerant, a first outlet, and a second outlet for withdrawl of said refrigerant;
• a moisture separator means having an input connected to said first outlet of said air-to-refrigerant heat exchanger means, and an outlet;
• a refrigerant system having an inlet connected to said second outlet of said air-to-refrigerant heat exchanger means and an outlet connected to said second inlet of said air-to-refrigerant heat exchanger means, said refrigerant system having at least a compressor and a heat exchanger;
• a moisture sorption means having at least one bed of moisture sorption material, said sorption means having an inlet connected to said output of said moisture separator means, and an outlet connected to said second input of said air-to-air heat exchanger means;
• and
• a purge system for selectively removing moisture from said bed of moisture sorption material, said purge system including a withdrawl line connected to said second outlet of said air-to-air heat exchanger means to obtain a portion of said product air to serve as purge air, a portion of said heat exchanger of said refrigerant system being in said withdrawl line to heat said purge air with heated refrigerant, and means for selectively applying said heated air from said portion of said heat exchanger to said bed for said selective removal of moisture from said moisture sorption material.

An improved drying system for removing moisture from air used in pneumatic systems to produce product air having a dew point of about -40 to about -100 degrees Fahrenheit, which comprises:

• an air-to-air heat exchanger means to provide a precooling of inlet air to said drying system, said air-to-air heat exchanger means having a first inlet to receive said input air, a second input, a first output for withdrawing precooled air and a second outlet for delivery of said product air to said pneumatic system, said air-to-air heat exchanger means having concentric tubes and wherein said inlets and outlets of said air-to-air heat exchanger means provide for counter current flow;
• an air-to-refrigerant heat exchanger means, said air-to-refrigerant heat exchanger means having a first inlet connected to said first outlet of said air-to-air heat exchanger means to receive said precooled air, a second inlet to receive a refrigerant, a first outlet, and a second outlet for withdrawl of said refrigerant, said air-to-refrigerant heat exchanger means having concentric tubes and wherein said inlets and outlets of said air-to-refrigerant heat exchanger means provide for counter current flow of said precooled air and said refrigerant;
• a refrigerant system having an inlet connected to said second outlet of said air-to-refrigerant heat exchanger means and an outlet connected to said second inlet of said air-to-refrigerant heat exchanger means, said refrigerant system having at least a compressor and a heat exchanger;
• a moisture separator means having an input connected to said first outlet of said air-to-refrigerant heat exchanger means, and an outlet;
• a moisture sorption means having an inlet connected to said output of said moisture separator means and an outlet connected to said second input of said air-to-air heat exchanger means, said sorption means having first and second beds of desiccant material and valve means connected to said first and second beds for selectively choosing between said first and second beds for sorption of moisture;
• a purge system for selectively removing moisture from said first and second beds of desiccant, said purge system including a withdrawl line connected to said second outlet of said air-to-air heat exchanger means to obtain a portion of said product air to serve as purge air, a portion of said heat exchanger of said refrigerant system being in said withdrawl line to heat said purge air with heated refrigerant, and further valve means for selectively applying said heated purge air to said beds of desiccant for selective removal of moisture from said desiccant of one bed while moisture sorption occurs on an alternate bed.