Process integration for natural gas liquid recovery

1. A natural gas liquid recovery system comprising:

a first chill down separator;

a second chill down separator;

a third chill down separator;

a de-methanizer column configured to receive at least one hydrocarbon stream and separate 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;

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 in the natural gas liquid recovery system to one or more of a plurality of cold process streams in the natural gas liquid recovery system, the plurality of hot process streams comprising:

a feed gas;

a first chill down liquid from the first chill down separator;

a dehydrated first chill down vapor from one or more feed gas dehydrators of the natural gas liquid recovery system;

a second chill down liquid from the second chill down separator;

a second chill down vapor from the second chill down separator; and

a high pressure residue gas from the third chill down separator, and the plurality of cold process streams comprising:

an overhead low pressure residue gas from the de-methanizer column;

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;

a refrigeration system configured to receive heat through the cold box, the refrigeration system comprising:

a primary refrigerant comprising a first mixture of hydrocarbons; and

a subcooler in fluid communication with the cold box, the subcooler configured to transfer heat between the primary refrigerant and a vapor phase of the primary refrigerant;

a turbo-expander in fluid communication with the de-methanizer column, the turbo-expander configured to use work from an expanding gas to compress the sales gas from the de-methanizer column; and

the one or more feed gas dehydrators positioned downstream of the first chill down separator, wherein:

each of the first chill down separator, the second chill down separator, and the third chill down separator are in fluid communication with the cold box,

the first chill down separator configured to separate the feed gas into a liquid phase and a refined gas phase,

the one or more feed gas dehydrators configured to remove water from the refined gas phase to produce the dehydrated first chill down vapor,

the de-methanizer column is in fluid communication with the cold box, and

the cold box is configured to transfer heat from the first chill down liquid to the overhead low pressure residue gas across five of the compartments of the cold box, from the dehydrated first chill down vapor to the overhead low pressure residue gas across three of the compartments of the cold box, from the second chill down liquid to the overhead low pressure residue gas across two of the compartments of the cold box, from the second chill down vapor to the overhead low pressure residue gas across five of the compartments of the cold box, and from the high pressure residue gas to the overhead low pressure residue gas across two of the compartments of the cold box.

2. The natural gas liquid recovery system of claim 1 , wherein the feed gas comprises a second mixture of hydrocarbons.

3. The natural gas liquid recovery system of claim 2 , wherein the first mixture comprises on a mole fraction basis of 60% to 70% of C3 hydrocarbon and 30% to 40% C4 hydrocarbon.

4. The natural gas liquid recovery system of claim 2 , wherein the sales gas comprising predominantly of methane comprises at least 98.6 mol % of methane, and the natural gas liquid comprising predominantly of hydrocarbons heavier than methane comprises at least 99.5 mol % of hydrocarbons heavier than methane.

5. The natural gas liquid recovery system of claim 2 , further comprising:

a feed pump configured to send a hydrocarbon liquid to the de-methanizer column;

a natural gas liquid pump configured to send natural gas liquid from the de-methanizer column; and

a storage system configured to hold an amount of natural gas liquid from the de-methanizer column.

6. The natural gas liquid recovery system of claim 2 , wherein the one or more feed gas dehydrators comprise a molecular sieve.

7. The natural gas liquid recovery system of claim 2 , further comprising a liquid dehydrator configured to remove water from the liquid phase.

8. The natural gas liquid recovery system of claim 7 , wherein the liquid dehydrator comprises a bed of activated alumina.

9. 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 first chill down liquid from a first chill down separator of a natural gas liquid recovery system;

a dehydrated first chill down vapor from one or more feed gas dehydrators of the natural gas liquid recovery system;

a second chill down liquid from a second chill down separator of the natural gas liquid recovery system;

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 natural gas liquid recovery system, and the plurality of cold process streams comprising:

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;

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; and

transferring heat to a refrigeration system through the cold box, the refrigeration system comprising:

a primary refrigerant comprising a first mixture of hydrocarbons; and

a subcooler in fluid communication with the cold box;

transferring heat from the primary refrigerant to a vapor phase of the primary refrigerant using the subcooler;

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 across five of the compartments of the cold box;

transferring heat from the dehydrated first chill down vapor to the overhead low pressure residue gas across three of the compartments of the cold box;

transferring heat from the second chill down liquid to the overhead low pressure residue gas across two of the compartments of the cold box;

transferring heat from the second chill down vapor to the overhead low pressure residue gas across five of the compartments of the cold box; and

transferring heat from the high pressure residue gas to the overhead low pressure residue gas across two of the compartments of the cold box.

10. The method of claim 9 , wherein the feed gas comprises a second mixture of hydrocarbons.

11. The method of claim 10 , wherein the first mixture comprises on a mole fraction basis of 60% to 70% of C3 hydrocarbon and 30% to 40% C4 hydrocarbon.

12. The method of claim 10 , wherein the sales gas comprising predominantly of methane comprises at least 98.6 mol % of methane, and the natural gas liquid comprising predominantly of hydrocarbons heavier than methane comprises at least 99.5 mol % of hydrocarbons heavier than methane.

13. The method of claim 10 , further comprising:

sending a hydrocarbon liquid to the de-methanizer column using a feed pump;

sending natural gas liquid from the de-methanizer column using a natural gas liquid pump; and

storing an amount of natural gas liquid from the de-methanizer column in a storage system.

14. The method of claim 10 , further comprising flowing a fluid from the cold box to the first chill down separator.

15. The method of claim 14 , further comprising condensing at least a portion of the feed gas in at least one compartment of the cold box.

16. The method of claim 15 , wherein the one or more feed gas dehydrators comprise a molecular sieve.

17. The method of claim 15 , further comprising removing water from the liquid phase using a liquid dehydrator comprising a bed of activated alumina.

18. 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;

a first chill down liquid from a first chill down separator of the natural gas liquid recovery system;

a dehydrated first chill down vapor from one or more feed gas dehydrators of the natural gas liquid recovery system;

a second chill down liquid from a second chill down separator of the natural gas liquid recovery system;

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 natural gas liquid recovery system;

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 column of the natural gas liquid recovery system;

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;

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 one of the one or more cold process streams is the only stream that flows through only one of the plurality of compartments, and the cold box is configured to transfer heat from the first chill down liquid to the overhead low pressure residue gas across five of the compartments of the cold box, from the dehydrated first chill down vapor to the overhead low pressure residue gas across three of the compartments of the cold box, from the second chill down liquid to the overhead low pressure residue gas across two of the compartments of the cold box, from the second chill down vapor to the overhead low pressure residue gas across five of the compartments of the cold box, and from the high pressure residue gas to the overhead low pressure residue gas across two of the compartments of the cold box.

19. The system of claim 18 , wherein the one or more hot refrigerant streams have compositions different from the one or more cold refrigerant streams.

20. The system of claim 18 , wherein at least one of the one or more hot refrigerant streams transfers heat to at least one of the one or more cold process streams and at least one of the one or more cold refrigerant streams.

21. The system of claim 18 , wherein a total number of compartments is 17.