Method and apparatus for reducing process disturbances during pressurization of an adsorber in an air separation unit

A method for reducing process disturbances during pressurization of an adsorber in an air separation unit, wherein the air separation unit comprises a front end purification unit, a main air compressor, a cold box having a main heat exchanger and a distillation column system disposed therein, a booster air compressor, and an air buffer tank, wherein the front end purification unit comprises a first adsorber and a second adsorber, the method comprising the steps of:

• compressing an air stream in a main air compressor to form a compressed main air stream;
• purifying the compressed main air stream in the front end purification unit to remove water and carbon dioxide to form a dry main air stream;
• sending a first portion of the dry main air stream to the cold box for cooling and rectification therein;
• boosting a second portion of the dry main air stream to a higher pressure PH in the booster air compressor to produce a boosted air stream;
• sending a first portion of the boosted air stream to the cold box for cooling and rectification therein;
• and
• sending a second portion of the boosted air stream to the air buffer tank,
• wherein each of the adsorbers of the front end purification unit undergoes a processing cycle comprising a regeneration cycle, a pressurization cycle, and an adsorption cycle,
• wherein during the pressurization cycle, a pressurized air stream is withdrawn from the air buffer tank and introduced to the adsorber that is undergoing pressurization.

An apparatus for reducing process disturbances during pressurization of an adsorber in an air separation unit, wherein the apparatus comprises:

• a main air compressor configured to compress an air stream to form a compressed main air stream;
• a front end purification unit configured to purify the compressed main air stream of water and carbon dioxide to form a dry main air stream, wherein the front end purification unit comprises two adsorbers, wherein each adsorber is configured to operate with an adsorption cycle, a regeneration cycle, and a pressurization cycle;
• a booster air compressor in fluid communication with the front end purification unit, wherein the booster air compressor is configured to boost a second portion of the dry main air stream to a higher pressure PH to form a boosted air stream;
• an air buffer tank having an air inlet in fluid communication with an outlet of the booster air compressor, wherein the air buffer tank is configured to receive a second portion of the boosted air stream, wherein an outlet of the air buffer tank is in fluid communication with the front end purification unit;
• a cold box in fluid communication with the front end purification unit and the outlet of the booster air compressor, wherein the cold box is configured to receive the first portion of the dry main air stream and the first portion of the boosted air stream, wherein the cold box houses a main heat exchanger and a distillation column system, wherein the main heat exchanger is configured to cool the first portion of the dry main air stream and the first portion of the boosted air stream to a cryogenic temperature suitable for rectification of air, wherein the distillation column system is configured to receive the first portion of the dry main air stream and the first portion of the boosted air stream from the main heat exchanger after cooling, wherein the distillation column system is configured to separate the dry main air stream and the boosted air stream into nitrogen and oxygen;
• wherein during a pressurization cycle of each adsorber, a valve located between the air buffer tank and the front end purification unit is configured to open to allow for dry air to flow from the air buffer tank to the adsorber,
• wherein the valve is configured to close, thereby stopping the flow of dry air to the adsorber, once the pressurization cycle is completed.