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:
• the feed gas, wherein the feed gas is flowed to a liquid recovery section of a gas processing plant;
• a first chill down liquid from a first chill down separator of the liquid recovery section;
• a dehydrated first chill down vapor from one or more feed gas dehydrators of the liquid recovery section;
• a second chill down liquid from a second chill down separator of the liquid recovery section;
• a second chill down vapor from the second chill down separator;
• and
• a high pressure residue gas from a third chill down separator of the liquid recovery section, and the plurality of cold process streams comprising:
• an overhead low pressure residue gas from a de-methanizer column of the liquid recovery section;
• a de-methanizer reboiler feed from the de-methanizer column;
• a first side draw from the de-methanizer column;
• a second side draw from the de-methanizer column;
• and
• a third side draw from the de-methanizer column;
• transferring heat to a refrigeration system through the cold box, the refrigeration system comprising a primary refrigerant comprising a first mixture of hydrocarbons;
• flowing, to the de-methanizer column in fluid communication with the cold box, at least one hydrocarbon stream originating from the feed gas;
• separating, using the de-methanizer column, the at least one hydrocarbon stream into a vapor stream comprising a sales gas comprising predominantly of methane and a liquid stream comprising a natural gas liquid comprising predominantly of hydrocarbons heavier than methane;
• expanding a gas stream through a turbo-expander in fluid communication with the de-methanizer column to produce expansion work;
• using the expansion work to compress the sales gas from the de-methanizer column;
• separating the feed gas into a liquid phase and a refined gas phase using the first chill down separator;
• and
• removing water from the refined gas phase using the one or more feed gas dehydrators to produce the dehydrated first chill down vapor, 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 first chill down liquid to the overhead low pressure residue gas through four of the compartments of the cold box, from the dehydrated first chill down vapor to the overhead low pressure residue gas through two of the compartments of the cold box, from the second chill down liquid to the overhead low pressure residue gas through two of the compartments of the cold box, from the second chill down vapor to the overhead low pressure residue gas through five of the compartments of the cold box, and from the high pressure residue gas to the overhead low pressure residue gas through two of the compartments of the cold box.

A system comprising:

• a cold box comprising a plurality of compartments that segment a plate-fin heat exchanger into a plurality of sections, each compartment of the cold box configured to transfer heat from one or more of a plurality of hot process streams to one or more of a plurality of cold process streams;
• the plurality of hot process streams, each of the plurality of hot process streams flowing through one or more of the plurality of compartments, the plurality of hot process streams comprising:
• a feed gas of a liquid recovery section of a gas processing plant;
• a first chill down liquid from a first chill down separator of the liquid recovery section;
• a dehydrated first chill down vapor from one or more feed gas dehydrators of the liquid recovery section;
• a second chill down liquid from a second chill down separator of the liquid recovery section;
• a second chill down vapor from the second chill down separator;
• and
• a high pressure residue gas from a third chill down separator of the liquid recovery section;
• the plurality of cold process streams, each of the plurality of cold process streams flowing through one or more of the plurality of compartments, the plurality of cold process streams comprising:
• an overhead low pressure residue gas from a de-methanizer of the liquid recovery section;
• a de-methanizer reboiler feed from the de-methanizer;
• a first side draw from the de-methanizer;
• a second side draw from the de-methanizer;
• and
• a third side draw from the de-methanizer;
• and
• a mixed refrigerant stream flowing through one or more of the plurality of compartments, the mixed refrigerant stream comprising a mixture on a mole fraction basis of 63% to 73% of C3 hydrocarbon and 27% to 37% C4 hydrocarbon, wherein the cold box is configured to transfer heat from the first chill down liquid to the overhead low pressure residue gas through four of the compartments of the cold box, from the dehydrated first chill down vapor to the overhead low pressure residue gas through two of the compartments of the cold box, from the second chill down liquid to the overhead low pressure residue gas through two of the compartments of the cold box, from the second chill down vapor to the overhead low pressure residue gas through five of the compartments of the cold box, and from the high pressure residue gas to the overhead low pressure residue gas through two of the compartments of the cold box.