Configurations and methods for nitrogen rejection, LNG and NGL production from high nitrogen feed gases

Patent metadata

Field	Value
Publication number	US-9920986-B2
Application number	US-201615284823-A
Country	US
Kind code	B2
Filing date	Oct 4, 2016
Priority date	Feb 28, 2014
Publication date	Mar 20, 2018
Grant date	Mar 20, 2018

Abstract

Variable N2 content in feed gas ranging from 3 mol % to 50 mol % can be rejected from the process using a feed exchanger that is fluidly coupled with a cold separator and a single fractionation column to produce a nitrogen vent stream and streams that are suitable to be further processed for NGL recovery and LNG production.

First claim

What is claimed is:

1. A plant with a nitrogen removal unit and a natural gas liquids recovery unit, comprising:
a feed gas source configured to provide a hydrocarbonaceous feed gas having a CO2 content of equal or less than 50 ppmv, a water content of equal or less than 0.1 ppmv, and a nitrogen content of at least 3 mol %;
a heat exchanger configured to receive and cool the hydrocarbonaceous feed gas to a temperature that condenses C3+ components in the hydrocarbonaceous feed gas;
a phase separator configured to receive the cooled hydrocarbonaceous feed gas and to separate the condensed C3+ components as a liquid stream from a vapor stream comprising C1, C2, and nitrogen;
a conduit fluidly coupled to the phase separator and configured to transport the liquid stream to a natural gas liquids recovery unit;
a refluxed fractionation column configured to receive the vapor stream and to produce a nitrogen-enriched overhead product and a nitrogen-depleted bottom product;
a reflux condenser configured to partially condense the nitrogen-enriched overhead product using refrigeration of a pressure-reduced first portion of the nitrogen-depleted bottom product to thereby produce a liquid reflux to the fractionation column and a gaseous nitrogen vent stream; and
a natural gas liquefaction unit fluidly coupled to the refluxed fractionation column and configured to receive the first portion of the nitrogen-depleted bottom product and a second portion of the nitrogen-depleted bottom product.

2. The plant of claim 1 , wherein the heat exchanger is further configured to receive and cool the vapor stream to at least partially condense the vapor stream.

3. The plant of claim 1 , wherein the heat exchanger and the reflux condenser are further configured to heat the gaseous nitrogen vent stream.

4. The plant of claim 1 , wherein the heat exchanger is further configured to receive and heat the second portion of the nitrogen-depleted bottom product.

5. The plant of claim 1 further comprising a compressor configured to re-compress the second portion of the nitrogen-depleted bottom product.

6. The plant of claim 1 , wherein the natural gas liquids recovery unit is configured to produce a vapor product, and further comprising a vapor conduit that is fluidly coupled to the natural gas liquefaction unit such that the vapor product is fed to the natural gas liquefaction unit.

Assignees

• Fluor Tech Corp

Inventors

• Mak John

Classifications

• F25J2260/20

  Integration in an installation for liquefying or solidifying a fluid stream · CPC title

• B01D53/002

  by condensation · CPC title

• F25J2205/04

  in the feed line, i.e. upstream of the fractionation step · CPC title

• F25J2200/72

  Refluxing the column with at least a part of the totally condensed overhead gas · CPC title

• C07C7/09 Primary

  by fractional condensation · CPC title