METHOD OF RECOVERY OF NATURAL GAS LIQUIDS FROM NATURAL GAS AT NGLS RECOVERY PLANTS

• US 20130333416A1
• Filed: 01/18/2012
• Published: 12/19/2013
• Est. Priority Date: 01/18/2011
• Status: Abandoned Application

• Current Assignee: 1304338 Alberta, Ltd., 1304342 Alberta, Ltd.
• Original Assignee: 1304338 Alberta, Ltd.
• Inventors: Lourenco, Jose, Millar, MacKenzie
• Application Number:
  US13/980,548
• Publication Number:
  US 20130333416A1
• Time in Patent Office: Days
• US Class Current: 62/611
• CPC Class Codes: B01D 3/4211 of columns
• CPC Class Codes: C10G 2300/1025 Natural gas
• CPC Class Codes: C10G 5/06 by cooling or compressing
• CPC Class Codes: F25J 1/0022 Hydrocarbons, e.g. natural gas
• CPC Class Codes: F25J 2200/02 in a single pressure main column system
• CPC Class Codes: F25J 2200/70 Refluxing the column with a condensed part of the feed stream, i.e. fractionator top is stripped or self-rectified
• CPC Class Codes: F25J 2200/74 Refluxing the column with at least a part of the partially condensed overhead gas
• CPC Class Codes: F25J 2205/04 in the feed line, i.e. upstream of the fractionation step
• CPC Class Codes: F25J 2205/30 using a washing, e.g. "scrubbing" or bubble column for purification purposes
• CPC Class Codes: F25J 2205/50 using absorption, i.e. with selective solvents or lean oil, heavier CnHm and including generally a regeneration step for the solvent or lean oil
• CPC Class Codes: F25J 2210/62 Liquefied natural gas [LNG]; Natural gas liquids [NGL]; Liquefied petroleum gas [LPG]
• CPC Class Codes: F25J 2240/02 Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream
• CPC Class Codes: F25J 2270/904 by liquid or gaseous cryogen in an open loop
• CPC Class Codes: F25J 3/0209 Natural gas or substitute natural gas
• CPC Class Codes: F25J 3/0214 Liquefied natural gas
• CPC Class Codes: F25J 3/0233 separation of CnHm with 1 carbon atom or more
• CPC Class Codes: F25J 3/0238 separation of CnHm with 2 carbon atoms or more

Abstract

A method to recover natural gas liquids from natural gas streams at NGL recovery plants. The present invention relates to methods using liquid natural gas (LNG) as an external source of stored cold energy to reduce the energy and improve the operation of NGL distillation columns. More particularly, the present invention provides methods to efficiently and economically achieve higher recoveries of natural gas liquids at NGL recovery plants.

Claims

1. A method for recovery of natural gas liquids from natural gas using the cold energy stored in LNG comprising the step of:

The storage and supply of LNG as an external cooling source to control the operation and recovery of NGLs in a distillation column.

2. The method as defined in claim 1, providing LNG as a reflux stream by a temperature control of the overhead gas stream by mixing of LNG with the rising gas stream in the distillation column.

3. The method as defined in claim 1, providing LNG to directly mix with un-distilled expanded, feed gas to allow distillation column to operate at higher pressures without loss of recovery.

4. The method as defined in claim 1, providing LNG as a stripping gas for carbon dioxide concentration in NGL product stream.

5. method described in claim 1, providing LNG to cool an overhead stream to generate a second reflux stream for a dual reflux distillation column operation.

6. A method for recovery of natural gas liquids from a natural gas comprising the steps of:

positioning a storage vessel for liquid natural gas (LNG) at a NGL recovery plant facility that has at least one distillation column for recovering natural gas liquids (NGLs);

adding LNG from the storage vessel by direct mixing to control the temperature profile in a NGL distillation column, the temperature in the overhead product of the distillation column being controlled by controlling addition of LNG as a reflux stream, the temperature in the expanded feed gas to the distillation column being controlled by controlling addition of LNG as a tempering gas, the stripping of carbon dioxide from the NGL product stream being controlled by controlling the addition of LNG as stripping gas.

7. The NGL recovery plant as defined in claim 6, wherein LNG provides additional cooling energy to the inlet plant gas feed.

8. NGL recovery plant as defined in claim 6, wherein the use of LNG as an external cold energy source is used to increase the overall energy efficiency and recovery of NGLs.