Utilization of nitrogen-enriched streams produced in air separation units comprising split-core main heat exchangers

A process of separating air comprising:

• a) passing a feed air stream sequentially through a main air compressor, an air pre-cooling unit and an air purification unit to produce a main feed air stream, further compressing part of the main feed air stream in a booster air compressor to form a boosted pressure air stream having a higher pressure and a higher temperature than the main feed air stream;
• b) cooling another part of the main feed air stream in a low-pressure heat exchanger through indirect heat exchange with a first nitrogen-enriched stream produced in an air rectification unit comprising a first column, a second column and a condenser evaporator disposed at a bottom of the second column, wherein the first column is operated at a higher pressure than the second column, thereby producing a first feed air stream for feeding into the air rectification unit;
• c) partially cooling at least part of the boosted pressure air stream in a high-pressure heat exchanger through indirect heat exchange with a pumped oxygen liquid and a second nitrogen-enriched stream produced in the air rectification unit, followed by expansion in a first expander before feeding into the air rectification unit as a second feed air stream;
• d) cooling a second part of the boosted pressure air stream in the high-pressure heat exchanger through indirect heat exchange with the pumped oxygen liquid and the second nitrogen-enriched stream to produce a third feed air stream, followed by expansion in a second expander to produce an expanded third feed air stream for feeding into the air rectification unit;
• e) introducing a warmed second nitrogen-enriched stream formed after passing the second nitrogen-enriched stream through the high-pressure heat exchanger into a regeneration gas heater and the air purification unit for regeneration and introducing a warmed first nitrogen-enriched stream formed after passing the first nitrogen-enriched stream through the low-pressure heat exchanger into a further entity;
• wherein the warmed first nitrogen-enriched stream and the warmed second nitrogen-enriched stream are in flow communication and the warmed second nitrogen-enriched stream is of a higher temperature compared to the warmed first nitrogen-enriched stream,
• wherein the warmed first nitrogen-enriched stream and the warmed second nitrogen-enriched stream are in flow communication through a conjoint section,
• wherein the conjoint section intersects with a flow of the warmed first nitrogen-enriched stream at a first connection point disposed between the low-pressure heat exchanger and the further entity and interconnects with a flow of the warmed second nitrogen-enriched stream at a second connection point disposed between the high-pressure heat exchanger and the regeneration gas heater,
• wherein a flow balance of the first nitrogen-enriched stream to the second nitrogen-enriched stream is regulated by a first valve disposed between the high-pressure heat exchanger and the second connection point,
• wherein the first valve is controlled by a first flow indication controller disposed between the low-pressure heat exchanger and the first connection point.

A process of separating air comprising:

• a) passing a feed air stream sequentially through a main air compressor, an air pre-cooling unit and an air purification unit to produce a main feed air stream, further compressing part of the main feed air stream in a booster air compressor to form a boosted pressure air stream having a higher pressure and a higher temperature than the main feed air stream;
• b) cooling another part of the main feed air stream in a low-pressure heat exchanger through indirect heat exchange with a first nitrogen-enriched stream produced in an air rectification unit comprising a first column, a second column and a condenser evaporator disposed at a bottom of the second column, wherein the first column is operated at a higher pressure than the second column, thereby producing a first feed air stream for feeding into the air rectification unit;
• c) partially cooling at least part of the boosted pressure air stream in a high-pressure heat exchanger through indirect heat exchange with a pumped oxygen liquid and a second nitrogen-enriched stream produced in the air rectification unit, followed by expansion in a first expander before feeding into the air rectification unit as a second feed air stream;
• d) cooling a second part of the boosted pressure air stream in the high-pressure heat exchanger through indirect heat exchange with the pumped oxygen liquid and the second nitrogen-enriched stream to produce a third feed air stream, followed by expansion in a second expander to produce an expanded third feed air stream for feeding into the air rectification unit;
• e) introducing a warmed second nitrogen-enriched stream formed after passing the second nitrogen-enriched stream through the high-pressure heat exchanger into a regeneration gas heater and the air purification unit for regeneration and introducing a warmed first nitrogen-enriched stream formed after passing the first nitrogen-enriched stream through the low-pressure heat exchanger into a further entity;
• wherein the warmed first nitrogen-enriched stream and the warmed second nitrogen enriched stream are in flow communication and the warmed second nitrogen-enriched stream is of a higher temperature compared to the warmed first nitrogen-enriched stream,
• wherein the warmed first nitrogen-enriched stream and the warmed second nitrogen-enriched stream are in flow communication through a conjoint section,
• wherein the conjoint section intersects with a flow of the warmed first nitrogen-enriched stream at a first connection point disposed between the low-pressure heat exchanger and the further entity and interconnects with a flow of the warmed second nitrogen-enriched stream at a second connection point disposed between the high-pressure heat exchanger and the regeneration gas heater,
• wherein a flow to the further entity is regulated by a second valve disposed between the first connection point and the further entity,
• wherein the second valve is controlled by a second flow indication controller disposed between the second connection point and the regenerated gas heater.