Systems and methods for removing nitrogen during liquefaction of natural gas
AssigneeConocoPhillips Company
InventorsWill T. James, Matthew C. Gentry, Wesley R. Qualls
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Abstract
Implementations described and claimed herein provide systems and methods for removing nitrogen during liquefaction of natural gas. In one implementation, a nitrogen rejection unit is used in an LNG facility to remove nitrogen from natural gas during an LNG liquefaction process. The nitrogen rejection unit contains at least two columns and at least one 3-stream condenser, 2-stream condenser or a two 2-stream condenser.
Claims20
A method for removing nitrogen from a natural gas stream using a nitrogen rejection unit, the method comprising:
- routing the natural gas stream to an upstream nitrogen removal column;
- forming a first top stream and a first bottom stream in the upstream nitrogen removal column;
- routing a first portion of the first top stream to a first condenser;
- condensing, at least partially via indirect heat exchange, the first portion of the first top stream using the first condenser;
- routing a second portion of the first top stream to an intermediate nitrogen removal column, where a second top stream and a second bottom stream are formed;
- routing at least a portion of the second top stream to a second condenser;
- condensing, at least partially via indirect heat exchange, the portion of the second top stream using the second condenser before routing to a downstream nitrogen removal column;
- forming a third top stream and a third bottom stream in the downstream nitrogen removal column, wherein the third top stream includes nitrogen;
- and
- removing at least a portion of the third top stream from the nitrogen rejection unit.
A liquefied natural gas system comprising:
- an upstream nitrogen removal column of a nitrogen rejection unit forming a first top stream and a first bottom stream from a natural gas stream;
- an intermediate nitrogen removal column of the nitrogen rejection unit forming a second top stream and a second bottom stream;
- a downstream nitrogen removal column of the nitrogen rejection unit forming a third top stream and a third bottom stream, the third top stream including nitrogen, at least a portion of the third top stream being removed from the nitrogen rejection unit;
- a first condenser of the nitrogen rejection unit condensing, at least partially via indirect heat exchange, a portion of the first top stream;
- and
- a second condenser of the nitrogen rejection unit condensing, at least partially via indirect heat exchange, at least a portion of the second top stream before routing the portion of the second top stream to the downstream nitrogen removal column.
A nitrogen rejection unit comprising:
- an upstream nitrogen removal column forming a first top stream and a first bottom stream from a natural gas stream;
- an intermediate nitrogen removal column forming a second top stream and a second bottom stream;
- a downstream nitrogen removal column forming a third top stream and a third bottom stream, the third top stream including nitrogen;
- a first condenser condensing, at least partially, a portion of the first top stream;
- and
- a second condenser condensing, at least partially, at least a portion of the second top stream before routing the portion of the second top stream to the downstream nitrogen removal column.
Dependencies are inferred from the claim text.