Process integration for natural gas liquid recovery

A method for recovering natural gas liquid from a feed gas, the method comprising:

• transferring heat from a plurality of hot process streams to a plurality of cold process streams through a cold box, the cold box comprising a plurality of compartments that segment a plate-fin heat exchanger into a plurality of sections, wherein transferring heat from the plurality of hot process streams to the plurality of cold process streams through the cold box comprises transferring heat from one or more of the plurality of hot process streams to one or more of the plurality of cold process streams through each compartment of the cold box, the plurality of hot process streams comprising:
• a feed gas;
• a dehydrated first chill down vapor from one or more feed gas dehydrators of the natural gas liquid recovery system;
• and
• a second chill down vapor from a second chill down separator of the natural gas liquid recovery system, and the plurality of cold process streams comprising:
• a high pressure residue gas from a third chill down separator of the natural gas liquid recovery system;
• an overhead low pressure residue gas from a de-methanizer column of the natural gas liquid recovery system;
• a de-methanizer reboiler feed from the de-methanizer column;
• and
• a de-methanizer bottoms from the de-methanizer column;
• transferring heat to a refrigeration system through the cold box, the refrigeration system comprising a primary refrigerant loop in fluid communication with the cold box, the primary refrigerant loop comprising:
• flowing a primary refrigerant comprising a first mixture of hydrocarbons to a feed drum;
• reducing pressure of the primary refrigerant using a throttling valve downstream of the feed drum;
• separating the primary refrigerant into a primary refrigerant liquid phase and a primary refrigerant vapor phase using a refrigerant separator in fluid communication with the cold box and positioned downstream of the throttling valve;
• flowing at least a portion of the primary refrigerant liquid phase to the cold box;
• removing and accumulating liquid from a stream of vaporized primary refrigerant using a knockout drum;
• increasing pressure of the stream of vaporized primary refrigerant using a compressor positioned downstream of the knockout drum;
• fully condensing the stream of vaporized primary refrigerant using one or more coolers positioned downstream of the compressor;
• flowing the condensed primary refrigerant from the one or more coolers to a first side of a subcooler;
• flowing the condensed primary refrigerant from the first side of the subcooler to the cold box;
• and
• flowing the primary refrigerant vapor phase from the refrigerant separator to a second side of the subcooler, wherein transferring heat from the plurality of hot process streams to the plurality of cold process streams through the cold box comprises:
• transferring heat from the dehydrated first chill down vapor to the high pressure residue gas through six of the compartments of the cold box;
• transferring heat from the dehydrated first chill down vapor to the overhead low pressure residue gas through six of the compartments of the cold box;
• transferring heat from the dehydrated first chill down vapor to the de-methanizer reboiler feed through one of the compartments of the cold box;
• and
• transferring heat from the dehydrated first chill down vapor to the de-methanizer bottoms through two of the compartments of the cold box.

A system comprising:

• a first chill down separator;
• a second chill down separator;
• a third chill down separator;
• a de-methanizer column;
• one or more feed gas dehydrators positioned downstream of the first chill down separator;
• a cold box comprising a plurality of compartments;
• a plurality of hot process streams, each of the one or more hot process streams flowing through one or more of the plurality of compartments, the plurality of hot process streams comprising:
• a feed gas;
• a dehydrated first chill down vapor from the one or more feed gas dehydrators;
• and
• a second chill down vapor from the second chill down separator;
• a plurality of cold process streams, each of the one or more cold process streams flowing through one or more of the plurality of compartments, the plurality of cold process streams comprising:
• a high pressure residue gas from the third chill down separator;
• an overhead low pressure residue gas from the de-methanizer column;
• a de-methanizer reboiler feed from the de-methanizer column;
• and
• a de-methanizer bottoms from the de-methanizer column;
• one or more hot refrigerant streams, each of the one or more hot refrigerant streams flowing through one or more of the plurality of compartments;
• and
• one or more cold refrigerant streams, each of the one or more cold refrigerant streams flowing through one or more of the plurality of compartments, wherein the cold box is configured to transfer heat from the dehydrated first chill down vapor to the high pressure residue gas through six of the compartments of the cold box, from the dehydrated first chill down vapor to the overhead low pressure residue gas through six of the compartments of the cold box, from the dehydrated first chill down vapor to the de-methanizer reboiler feed through one of the compartments of the cold box, and from the dehydrated first chill down vapor to the de-methanizer bottoms through two of the compartments of the cold box.